Nonaqueous electrolytic solution containing magnesium ions, and electrochemical device using the same

ABSTRACT

A nonaqueous electrolytic solution containing magnesium ions which shows excellent electrochemical characteristics and which can be manufactured in a general manufacturing environment such as a dry room, and an electrochemical device using the same are provided. A Mg battery has a positive-electrode can  1 , a positive-electrode pellet  2  made of a positive-electrode active material or the like, a positive electrode  11  composed of a metallic net supporting body  3 , a negative-electrode cup  4 , a negative electrode  12  made of a negative-electrode active material  5 , and a separator  6  impregnated with an electrolytic solution  7  and disposed between the positive-electrode pellet and the negative-electrode active material. Metal Mg, an alkyl trifluoromethanesulfonate, a quaternary ammonium salt or/and a 1,3-alkylmethylimidazolium salt, more preferably, an aluminum halide are added to an ether system organic solvent and are then heated, and thereafter, more preferably, a trifluoroborane-ether complex salt is added thereto, thereby preparing the electrolytic solution. By adopting a structure that copper contacts the positive-electrode active material, the electrochemical device can be given a large discharge capacity.

TECHNICAL FIELD

The present invention relates to a nonaqueous electrolytic solutioncontaining therein magnesium ions, and an electrochemical device usingthe same.

BACKGROUND ART

A metal which is easy to emit an electron to become a cation, that is, ametal having a large ionization tendency is given as a material suitablefor a negative-electrode active material as one of basic constituentmaterials of a battery. In a battery using a nonaqueous electrolyticsolution, metal lithium is given as this example. The battery usingmetal lithium as a negative-electrode active material is structured inthe form of a battery using a nonaqueous electrolytic solution based ona combination of various kinds of positive-electrode active materialssuch as an oxide and a sulfide, thereby being commercialized. Thus, thatbattery is mainly used as a power source of a small portable electronicapparatus.

In recent years, for the purpose of enhancing the convenience,miniaturization, weight lighting, thinning, and an increased highfunction of the small portable electronic apparatuses have been steadilyadvanced year by year. Along therewith, a small size, a light weight, asmall width, and especially a large capacity are required for thebattery used as the power source of each of these apparatuses.Therefore, it can be said that the larger a capacity (mAh/g) per unitmass or a capacity (mAh/cm³) per unit volume of each of thenegative-electrode active material and the positive-electrode activematerial composing the battery is, the better.

Comparing the energy capacity per unit mass of the metal lithium withthat of other metals, the energy capacity of metal lithium (Li) islarger than that of any of other metals, and thus is superior to that ofany of other metals. For this reason, heretofore, many studies about thelithium secondary battery have been reported. However, the lithiumsecondary battery involves a problem in stability, and lithium islimited in terms of resources and is expensive.

An example of a study about a nonaqueous electrolytic solution systembattery using magnesium (Mg), as a metal having a higher energy densitythan that of lithium (Li), as the negative-electrode active material hasbeen reported as a next-generation high capacity battery (for example,refer to a Non-Patent Document 1 which will be described later).

Magnesium is abundant in terms of the resources, and is much moreinexpensive than lithium. In addition, metal magnesium has a largeenergy capacity per unit volume, and has a higher energy density thanthat of metal lithium. Moreover, when metal magnesium is used in thebattery, the high margin of safety can be expected. As described above,the magnesium secondary battery is the secondary battery which can coverthe shortcomings of the lithium secondary battery. On the basis of theserespects, at the present time, the development of the nonaqueouselectrolytic solution battery using metal magnesium as thenegative-electrode active material gains recognition as thenext-generation high capacity battery. As with this example, metalmagnesium and the magnesium ions are very promising materials as theelectrode active material in the electrochemical device, and theelectric charge carriers in the electrolytic solution, respectively.

The selection of the electrolytic solution is very important indesigning the electrochemical device using metal magnesium and themagnesium ions. For example, not only water and a protic organicsolvent, but also an ester class and a nonprotic organic solvent such asacrylonitrile cannot be used as the solvent composing the electrolyticsolution. The reason for this is because when these solvents are used, apassive state film through which none of the magnesium ions are notpassed is formed on a surface of metal magnesium. A problem about theformation of the passive state film becomes one of hindrances in puttingthe magnesium secondary battery into practical use.

An ether solution of a Grignard reagent (RMgX: R is either an arkylgroup or an aryl group, and X is any one of chlorine, bromine, andiodine) has been known as an electrolytic solution which does notinvolve the problem about the formation of the passive state film andwhich can electrochemically utilize magnesium since long ago. When thiselectrolytic solution is used, metal magnesium can be reversiblyprecipitated and dissolved. However, an oxidation and decompositionpotential of the electrolytic solution is as low as about 1.5 V relativeto an equilibrium potential of metal magnesium. Thus, a potential windowis insufficient for use of that electrolytic solution in theelectrochemical device (refer to a in FIG. 1 of the Non-Patent Document1 which will be described later).

With regard to the nonaqueous electrolytic solution not using theGrignard reagent, there are the Non-Patent Document 1, a Patent Document1, a Patent Document 2 and the like which will be described later.

Firstly, the following description is given in the Patent Document 1,which will be described later, entitling “Nonaqueous ElectrolyticSolution of High Energy, Rechargeable Electrochemical Cell.”

A nonaqueous electrolytic solution for use in an electrochemical cell iscomposed of (a) at least one organic solvent, and (b) at least oneelectrolytic solution active salt represented by a formulaM′^(+m)(ZR_(n)X_(q-n))_(m). In this formula, M′ is selected from thegroup consisting of magnesium, calcium, aluminum, lithium and sodium. Zis selected from the group consisting of aluminum, boron, phosphorus,antimony, and arsenic. R represents a group selected from the followinggroup, that is, the group consisting of alkyl, alkenyl, aryl, phenyl,benzyl, and amide. X is halogen (I, Br, Cl, F). m=1 to 3. WhenZ=phosphorus, antimony and arsenic, n=0 to 5, and q=6. When Z=aluminumand boron, n=0 to 3, and q=4.

In addition, the following description is given as Example 3 of theinvention in the Patent Document 1.

An electrochemical cell was composed of a Chevrel phase cathode, amagnesium metal anode, and an electrolytic solution containing therein aMg(AlCl₂BuEt)₂ salt in THF and was prepared. 25.7 mg of the cathode wasmade of a mixture of the Chevrel phase material in which copper wasleached out, and which contained therein 10 wt % carbon black and 10 wt% PVDF as a binder spread out in a stainless steel mesh. A solutionthereof was prepared from 0.25 mol of a Mg(AlCl₂BuEt)₂ salt in THF. Theanode was a disc of a pure magnesium metal having a diameter of 16 mm,and a thickness of 0.2 mm. The cell was packed in a stainless steel“coin cell” shape provided with a paper separator made of a glass fiber.The cell was subjected to the circulation of the standardcharge-discharge having a current density of 23.3 mA/g. A potentiallimit for the circulation was lied between 0.5 V in a perfectlydischarged state, and 1.8 V in a perfectly discharged state.

The battery was continuously subjected to the circulation for threemonths or more. A circulation possibility having the excellentcirculation is clearly obvious from FIG. 3 of the Patent Document 1, andcycles 340 to 345 are shown adjacent to first five cycles (cycles 1 to5). The result of the circulation is kept strong throughout theexperiments. A charge density obtained in each discharge is 61 mAh pergram of the cathode material.

In addition, a description about a potential difference dynamic behaviorof a Mg_(x)Mo₃S₄ electrode in a tetrahydrofuran (THF) solution of aMg(AlCl₂BuEt)₂ is given in the Non-Patent Document 1. Moreover, atypical charge-discharge behavior of a Mg—Mg_(x)Mo₃S₄ coin cell typebattery (an electrolyte is 0.25 M of Mg(AlCl₂BuEt)₂ in THF) is shownbased on a relationship between the number of cycles, and a specificdischarge capacity (mAhg⁻¹).

Next, the following description is given in the Patent Document 2, whichwill be described later, entitling “Magnesium Secondary Battery.”

The invention of the Patent Document 2 relates to a secondary battery inwhich a negative-electrode active material is a magnesium metal, and apositive-electrode active material is a transition metal compound whichcan carry out intercalation of a magnesium ion, and an electrolyticsolution is composed of an electrolyte containing therein a compoundincluding an atomic group in which an aromatic atomic group and onehalogen atom are linked to a magnesium atom, and a solvent composed ofan ether system compound liquid. It is said that a charge voltage can beset as being equal to or higher than 2.3 V with this secondary battery.

The electrolyte described above is preferably halogenophenyl magnesium(C₆H₅MgX(X═Cl, Br)). In addition, it is said that the electrolytedescribed above is preferably a polymer gel electrolyte containingtherein C₆H₅MgX(X═Cl, Br), and a polyethylene oxide (PEO).

In Example in which a THF solution of C₆H₅MgBr is used as anelectrolytic solution, a decomposition start voltage is about 3.8 V,whereas in Comparative Example in which a THF solution ofMg[Al(C₂H₅)₂Br₂]₂ is used as an electrolytic solution, a decompositionstart voltage is about 2.3 V, and the electrolytic solution is oxidizedeven at 2.2 V to be colored with brown. Therefore, it was made clearthat with the secondary battery shown in Example, the charge at the highvoltage is possible. In addition, it was shown that the electrolyticsolution used in the secondary battery has a high decomposition voltage.

In a word, according to the invention of the Patent Document 2, thesecondary battery is prepared in which the negative-electrode activematerial is the magnesium metal, and the positive-electrode activematerial is the transition metal compound which can carry out theintercalation of the magnesium ion, and the electrolytic solution ismade the electrolytic solution containing therein the electrolytecontaining therein the compound including the atomic group in which thearomatic atomic group and one halogen atom are linked to the magnesiumatom, and the solvent composed of the ether system compound liquid,whereby it is possible to obtain the secondary battery which has thehigh margin of safety, is inexpensive, and has the high electriccapacity density, and with which the high charge voltage is possible.

In addition, a study about a graphite fluoride as a positive-electrodeactive material for which a higher capacity than that of a molybdenumsulfide can be expected is reported (for example, refer to a Non-PatentDocument 2 which will be described later).

PRIOR ART DOCUMENT Patent Document

-   Patent Document 1:-   Japanese Unexamined Patent Application Publication No. 2003-512704    (paragraph 0017, paragraphs 0048 to 0049, FIG. 3)-   Patent Document 2:-   Japanese Patent Laid-Open No. 2004-259650 (paragraphs 0015 to 0019,    paragraph 0020, paragraphs 0034 to 0035)

Non-Patent Document

-   Non-Patent Document 1:-   D. Aurbach et al, “Prototype systems for rechargeable magnesium    batteries,” Nature 407, p. 724 to 727 (2000) (FIG. 3, FIG. 4,    left-column lines 41 to 56 in page 726)-   Non-Patent Document 2:-   Jerome Giraudet et al, “Magnesium batteries: Towards a first use of    graphite fluorides,” Journal of Power Sources 173 (2007) 592 to 598    (3.2.3 Effect of the electrolyte composition and of the    re-fluorimation treatment)

SUMMARY OF THE INVENTION Technical Problem

The electrolytic solution composed of the ether solution of the Grignardreagent involves such a problem that its oxidation decompositionpotential is as low as about +1.5 V relative to the equilibriumpotential of metal magnesium, and thus the potential window isinsufficient for use of that electrolytic solution in theelectrochemical device.

A raw material which is unstable for synthesis of the electrolyticsolution, and various kinds of solvents are used in the electrolyticsolution reported in the Patent Document 1 and the manufacturing processthereof is very complicated. For example, sincedichlorobutylethylmagnesium aluminate (Mg[AlCl₂(C₂H₅)(C₄H₉)]₂) used asan electrolyte salt is unstable in the atmosphere, the process formanufacturing the battery must be carried out in an inactive ambientatmosphere such as an argon box. For this reason, this battery cannot bemanufactured in a dry room as a general manufacturing environment of thebattery using the organic nonaqueous electrolytic solution. Therefore,it is thought that it is actually impossible to commercialize themagnesium battery reported in the Patent Document 1 without change.

In addition, it is described in the Patent Document 2 that thedecomposition start potential is +3.8 V. However, the inventor of thisapplication carried out the additional experiments in detail, and as aresult, it became clear that the THF solution having a concentration of0.1 mol/l of phenylmagnesiumbromide (C₆H₅MgBr) actually starts to bedecomposed around +2.0 V, and thus it was made clear that thedecomposition start voltage is not so high as to be described in thePatent Document 2.

A battery system in which a molybdenum sulfide is used as apositive-electrode active material, a magnesium metal is used as anegative electrode, and a tetrahydrofuran solution of organichaloaluminate magnesium is used as an electrolytic solution is proposedin the Non-Patent Document 1. However, in this battery system, thecapacity of the molybdenum sulfide as the positive-electrode activematerial is small, and thus for the battery system, it is very difficultto realize the increased high capacity for the existing battery.

In a graphite fluoride described in the Non-Patent Document 2, atheoretical capacity due to one electron reduction reaction is 860 mAh/g(2000 mAh/cc or more) which largely exceeds that of the molybdenumsulfide described in the Non-Patent Document 1. Thus, the graphitefluoride holds a potentiality that the very large capacity can berealized in terms of the magnesium battery. It is noted that although inthe Non-Patent Document 2, 572 mAh/g is obtained as the dischargecapacity of the graphite fluoride, this value is merely 66.5% of thetheoretical capacity and thus in the future, it is desired to furtherincrease the capacity.

The present invention has been made in order to solve the problems asdescribed above, and it is therefore an object of the present inventionto provide a nonaqueous electrolytic solution containing thereinmagnesium ions which is capable of sufficiently bringing out excellentcharacteristics of metal magnesium as a negative-electrode activematerial, and is also capable of being manufactured in a generalenvironment such as a dry room, and an electrochemical device using thesame.

Technical Solution

That is to say, the present invention relates to a nonaqueouselectrolytic solution containing therein magnesium ions in which metalmagnesium, alkyl trifluoromethanesulfonate (RCF₃O₃) (for example, methyltrifluoromethanesulfonate in an embodiment which will be describedlater), and a quaternary ammonium salt (R¹R²R³R⁴N⁺Z⁻) (for example,tetrafluoro tetrabutyl ammonium borate in the embodiment which will bedescribed later) or/and a 1,3-alkyl methylimidazoliumsalt([R(C₃H₃N₂)CH₃]⁺X⁻) (for example,1-ethyl-3-methylimidazoliumbis(trifluoromethanesulfonyl)imide in theembodiment which will be described later) are added to an ether systemorganic solvent, and magnesium ions are dissolved in the ether systemorganic solvent (for example, 1,2-dimethoxyethane in the embodimentwhich will be described later).

In this regard, R in the general formula RCF₃SO₃ representing alkyltrifluoromethanesulfonate, R is either a methyl group or an ethyl group.In addition, each of R¹, R², R³, and R⁴ in the general formulaR¹R²R³R⁴N⁺Z⁻ representing the quaternary ammonium salt described aboveis either an alkyl group or an aryl group, and Z⁻ is any one of achloride ion (Cl⁻), a boromide ion (Br⁻), an iodine ion (I⁻), an aceticacid ion (CH₃COO⁻), a perchloric acid ion (ClO₄ ⁻), a tetrafluoroboricacid (BF₄ ⁻), a hexafluorophosphoric acid ion (PF₆ ⁻), ahexafluoroarsenic acid ion (AsF₆ ⁻), a perfluoroalkylsulfonic acid ion(Rf1SO₃ ⁻: RF1 is a perfluoroalkyl group), and a perfluoroalkylsulfonylimide ion ((Rf2SO₂)₂N⁻): Rf2 is a perfluoroalkyl group).

In addition, in the general formulas [R(C₃H₃N₂)CH₃]⁺X⁻ representing the1,3-alkyl methylimidazolium salt, R is a methyl group, an ethyl group ora butyl group, and X⁻ is any one of a tetrafluoroboric acid ion (BF₄ ⁻)or a bis(trifluoromethanesulfonyl)imide ion ((SO₂CF₃)₂N⁻).

In addition, the present invention relates to an electrochemical devicehaving the nonaqueous electrolytic solution containing magnesium ionsdescribed above (for example, an electrolytic solution 7 in anembodiment which will be described later), a first electrode (forexample, a positive electrode 11 in the embodiment which will bedescribed later, and a second electrode (for example, a negativeelectrode 12 in the embodiment which will be described later), in whichthe electrochemical device is structured in such a way that an activematerial of the second electrode is oxidized to generate magnesium ions.

In addition, the present invention relates to an electrochemical devicehaving a negative-electrode active material containing therein either amagnesium metal or a magnesium alloy, and a positive-electrode mixturecontaining therein a positive-electrode active material made from agraphite fluoride, and copper (for example, composed of apositive-electrode active material, a conductive material, a binder, andcopper powder in the embodiment which will be described later), andstructured as a magnesium battery.

In addition, the present invention relates to an electrochemical devicehaving a negative-electrode active material containing therein either amagnesium metal or a magnesium alloy, a positive-electrode mixturecontaining therein a positive-electrode active material made from agraphite fluoride, (for example, composed of a positive-electrode activematerial, a conductive material, and a binder in the embodiment whichwill be described later), a positive-electrode power collecting bodymade of a conductive material covered with copper, or/and copper and/ora positive-electrode can having an inner surface covered with coppercontacting the positive-electrode active material, and structured as amagnesium battery.

ADVANTAGEOUS EFFECTS

According to the present invention, metal magnesium, alkyltrifluoromethanesulfonate (RCF₃SO₃), and the quaternary ammonium salt(R¹R²R³R⁴N⁺Z⁻) or/and the 1,3-alkyl methylimidazolium salt([R(C₃H₃N₂)CH₃]⁺X⁻) are added to the ether system organic solvent, andthe magnesium ions are dissolved in the ether system organic solvent.Therefore, it is possible to provide the nonaqueous electrolyticsolution containing therein magnesium ions which is capable ofsufficiently bringing out the excellent characteristics of metalmagnesium as the negative-electrode active material, and is also capableof being manufactured in the general environment such as the dry room.

In addition, according to the present invention, the electrochemicaldevice has the nonaqueous electrolytic solution containing magnesiumions described above, the first electrode, and the second electrode, andis structured in such a way that the active material of the secondelectrode is oxidized to generate the magnesium ions. Therefore, it ispossible to provide the electrochemical device which is capable ofsufficiently bringing out the excellent characteristics of metalmagnesium.

In addition, according to the present invention, the electrochemicaldevice has the negative-electrode active material containing thereineither the magnesium metal or the magnesium alloy, and thepositive-electrode mixture containing therein the positive-electrodeactive material made from the graphite fluoride, and copper, and has thestructure that copper is mixed with the positive-electrode activematerial, or is covered with the positive-electrode active material tobe contained in the positive-electrode mixture, thereby contacting thepositive-electrode active material, and the positive-electrode mixturecontains therein copper (hereinafter referred to as a first structure).Therefore, it is possible to provide the electrochemical device which iscapable of greatly increasing the discharge capacity of the graphitefluoride, and which is structured as the magnesium battery having thedischarge capacity corresponding up to about 99% relative to thetheoretical capacity based on the one electron reduction reaction.

In addition, according to the present invention, the electrochemicaldevice has the negative-electrode active material containing thereineither the magnesium metal or the magnesium alloy, thepositive-electrode mixture containing therein the positive-electrodeactive material made from the graphite fluoride, the positive-electrodepower collecting body made of the conductive material covered withcopper or/and copper, and/or the positive-electrode can having the innersurface covered with copper contacting the positive-electrode activematerial. Therefore, when the positive-electrode power collecting bodyis made of the conductive material covered with copper and/or copper(hereinafter referred to as a second structure), copper contacts thepositive-electrode active material. Thus, it is possible to provide theelectrochemical device structured as the magnesium battery which has thedischarge capacity corresponding to 95.8% relative to the theoreticalcapacity described above without increasing the capacity of the battery.When the inner surface of the positive-electrode can described above iscovered with copper and copper contacts the positive-electrode activematerial described above (hereinafter referred to as a third structure),it is possible to provide the magnesium battery which has the dischargecapacity corresponding to 93.3% relative to the theoretical capacitydescribed above without increasing the capacity of the battery. Inaddition, since the inner volume of the battery is not increased, thedischarge capacity per unit volume is prevented from being reduced.Moreover, in the second structure, the positive-electrode powercollecting body covered with copper only has to be used. Also, in thethird structure, the positive-electrode can having the inner surfacecoated with copper only has to be used. Therefore, the manufacturingcost is prevented from being increased without largely changing themethod of manufacturing the battery.

BRIEF DESCRIPTION OF DRAWINGS

[FIG. 1]

FIG. 1 is a cross sectional view showing a structure of a magnesiumbattery in an embodiment of the present invention.

[FIG. 2]

FIG. 2 is a diagram showing a relationship among concentrations of Mg,MeTFS, TBABF₄, AlCl₃, and BF₃DEE used in synthesis of an electrolyticsolution, a heating temperature, and a discharge capacity of a magnesiumbattery using the synthesized electrolytic solution in Example of thepresent invention.

[FIG. 3]

FIG. 3 is a diagram showing a relationship among the concentrations ofMg, MeTFS, TBABF₄, AlCl₃, and BF₃DEE used in the synthesis of theelectrolytic solution, the heating temperature, and the dischargecapacity of the magnesium battery using the synthesized electrolyticsolution in Examples of the present invention, and showing arelationship between a discharge capacity of a positive-electrode activematerial, and a MeTFS concentration.

[FIG. 4]

FIG. 4 is a diagram showing a relationship among the concentrations ofMg, MeTFS, TBABF₄, AlCl₃, and BF₃DEE used in the synthesis of theelectrolytic solution, the heating temperature, and the dischargecapacity of the magnesium battery using the synthesized electrolyticsolution in Examples of the present invention, and showing arelationship between a discharge capacity of a positive-electrode activematerial, and a TBABF₄ concentration.

[FIG. 5]

FIG. 5 is a diagram showing a relationship among the concentrations ofMg, MeTFS, TBABF₄, AlCl₃, and BF₃DEE used in the synthesis of theelectrolytic solution, the heating temperature, and the dischargecapacity of the magnesium battery using the synthesized electrolyticsolution in Examples of the present invention, and showing arelationship between the discharge capacity of the positive-electrodeactive material, and an AlCl₃ concentration.

[FIG. 6]

FIG. 6 is a diagram showing a relationship among the concentrations ofMg, MeTFS, TBABF₄, AlCl₃, and BF₃DEE used in the synthesis of theelectrolytic solution, the heating temperature, and the dischargecapacity of the magnesium battery using the synthesized electrolyticsolution in Examples of the present invention, and showing arelationship between the discharge capacity of the positive-electrodeactive material, and a Mg concentration.

[FIG. 7]

FIG. 7 is a diagram showing a relationship among the concentrations ofMg, MeTFS, TBABF₄, AlCl₃, and BF₃DEE used in the synthesis of theelectrolytic solution, the heating temperature, and the dischargecapacity of the magnesium battery using the synthesized electrolyticsolution in Examples of the present invention, and showing arelationship between the discharge capacity of the positive-electrodeactive material, and the heating temperature.

[FIG. 8]

FIG. 8 is a diagram showing a relationship among the concentrations ofMg, MeTFS, TBABF₄, AlCl₃, and BF₃DEE used in the synthesis of theelectrolytic solution, the heating temperature, and the dischargecapacity of the magnesium battery using the synthesized electrolyticsolution in Examples of the present invention, and showing arelationship between the discharge capacity of the positive-electrodeactive material, and the BF₃DEE concentration.

[FIG. 9]

FIG. 9 is a diagram showing a discharge capacity of a magnesium batteryusing an electrolytic solution which is synthesized by changing a kindof alkyl trifluoromethanesulfonate in Example 1 of the presentinvention.

[FIG. 10]

FIG. 10 is a diagram showing a discharge capacity of a magnesium batteryusing an electrolytic solution which is synthesized by changing a kindof quaternary ammonium salt in Example 1 of the present invention.

[FIG. 11]

FIG. 11 is a diagram showing a discharge capacity of a magnesium batteryusing an electrolytic solution which is synthesized by changing a kindof trifluoroborane-ether complex salt in Example 1 of the presentinvention.

[FIG. 12]

FIG. 12 is a view showing an example of structures of complexes each ofwhich is thought to be contained in the synthesized electrolyticsolution in Example 1 of the present invention.

[FIG. 13]

FIG. 13 is a diagram showing a relationship among concentrations of Mg,MeTFS, EMITFSI, AlCl₃, and BF₃DEE used in synthesis of an electrolyticsolution, a heating temperature, and a discharge capacity of a magnesiumbattery using the synthesized electrolytic solution in Example of thepresent invention.

[FIG. 14]

FIG. 14 is a diagram showing a relationship among concentrations of Mg,MeTFS, EMITFSI, AlCl₃, and BF₃DEE used in synthesis of an electrolyticsolution, a heating temperature, and a discharge capacity of a magnesiumbattery using the synthesized electrolytic solution in Examples of thepresent invention, and showing a relationship between a dischargecapacity of a positive-electrode active material, and the MeTFSconcentration.

[FIG. 15]

FIG. 15 is a diagram showing a relationship among concentrations of Mg,MeTFS, EMITFSI, AlCl₃, and BF₃DEE used in synthesis of an electrolyticsolution, a heating temperature, and a discharge capacity of a magnesiumbattery using the synthesized electrolytic solution in Examples of thepresent invention, and showing a relationship between a dischargecapacity of a positive-electrode active material, and the EMITFSIconcentration.

[FIG. 16]

FIG. 16 is a diagram showing a relationship among concentrations of Mg,MeTFS, EMITFSI, AlCl₃, and BF₃DEE used in synthesis of an electrolyticsolution, a heating temperature, and a discharge capacity of a magnesiumbattery using the synthesized electrolytic solution in Examples of thepresent invention, and showing a relationship between a dischargecapacity of a positive-electrode active material, and the AlCl₃concentration.

[FIG. 17]

FIG. 17 is a diagram showing a relationship among concentrations of Mg,MeTFS, EMITFSI, AlCl₃, and BF₃DEE used in synthesis of an electrolyticsolution, a heating temperature, and a discharge capacity of a magnesiumbattery using the synthesized electrolytic solution in Examples of thepresent invention, and showing a relationship between a dischargecapacity of a positive-electrode active material, and the Mgconcentration.

[FIG. 18]

FIG. 18 is a diagram showing a relationship among concentrations of Mg,MeTFS, EMITFSI, AlCl₃, and BF₃DEE used in synthesis of an electrolyticsolution, a heating temperature, and a discharge capacity of a magnesiumbattery using the synthesized electrolytic solution in Examples of thepresent invention, and showing a relationship between a dischargecapacity of a positive-electrode active material, and the heatingtemperature.

[FIG. 19]

FIG. 19 is a diagram showing a relationship among concentrations of Mg,MeTFS, EMITFSI, AlCl₃, and BF₃DEE used in synthesis of an electrolyticsolution, a heating temperature, and a discharge capacity of a magnesiumbattery using the synthesized electrolytic solution in Examples of thepresent invention, and showing a relationship between a dischargecapacity of a positive-electrode active material, and the BF₃DEEconcentration.

[FIG. 20]

FIG. 20 is a diagram showing a discharge capacity of a magnesium batteryusing an electrolytic solution which is synthesized by changing a kindof alkyl trifluoromethanesulfonate in Example 11 of the presentinvention.

[FIG. 21]

FIG. 21 is a diagram showing a discharge capacity of a magnesium batteryusing an electrolytic solution which is synthesized by changing a kindof 1,3-alkylmethylimidazolium salt in Example 11 of the presentinvention.

[FIG. 22]

FIG. 22 is a diagram showing a discharge capacity of a magnesium batteryusing an electrolytic solution which is synthesized by changing a kindof trifluoroborane-ether complex salt in Example 11 of the presentinvention.

[FIG. 23]

FIG. 23 is a view showing an example of structures of complexes each ofwhich is thought to be contained in the synthesized electrolyticsolution in Example 11 of the present invention.

[FIG. 24]

FIG. 24 is a diagram showing a relationship between a mass ratio ofcopper to a graphite fluoride (copper/graphite fluoride), and adischarge capacity of the graphite fluoride when copper is added to apositive-electrode mixture in Examples of the present invention.

[FIG. 25]

FIG. 25 is a graph showing a change in positive-electrode dischargecapacity about Comparative Example 15 and Example 21-10 of the presentinvention.

[FIG. 26]

FIG. 26 is a diagram showing a discharge capacity of the graphitefluoride when a positive-electrode power collecting body made of copperis used in Examples of the present invention.

[FIG. 27]

FIG. 27 is a diagram showing the discharge capacity of the graphitefluoride when an inner surface of a positive-electrode can is coveredwith copper in Examples of the present invention.

MODE FOR CARRYING OUT THE INVENTION

In a nonaqueous electrolytic solution containing therein magnesium ionsof the present invention, it is better to adopt a structure that analuminum halide (AlY₃) is added to the ether system organic solventdescribed above. In this regard, Y in the general formula AlY₃representing the aluminum halide is any one of chlorine (Cl), bromine(Br), and iodine (I). According to this structure, it is possible toincrease a positive-electrode discharge capacity of the magnesiumbattery using the nonaqueous electrolytic solution containing thereinthe magnesium ions.

In addition, it is better to adopt a structure that the aluminum halidedescribed above is an aluminum chloride, and the aluminum halide isadded at a ratio of 1.0 mol or less per 1.0 mol of metal magnesiumdescribed above. According to this structure, it is possible to providethe electrolytic solution which can increase the positive-electrodedischarge capacity of the magnesium battery using the nonaqueouselectrolytic solution containing therein the magnesium ions. With thestructure that the aluminum halide is added at a ratio of exceeding 1.0mol per 1.0 mol of metal magnesium, the discharge capacity of themagnesium battery is reduced.

In addition, it is better to adopt a structure that thetrifluoroborane-ether complex salt (BF₃(ether)) described above is addedto the ether system organic solvent described above. According to thisstructure, it is possible to increase the positive-electrode dischargecapacity of the magnesium battery using the nonaqueous electrolyticsolution containing therein the magnesium ions.

In addition, it is better to adopt a structure that at least one kind oftrifluoroborane-ether complex salt (BF₃(ether)) selected from the groupconsisting of a trifluoroborane-dimethyl ether complex salt, atrifluoroborane-ethyl methyl ether complex salt, atrifluoroborane-diethyl ether complex salt, a trifluoroborane-n-dibutylether complex salt, and a trifluoroborane-tetrahydrofuran complex saltis added. Ether in the general formula BF₃(ether) representing thetrifluoroborane-ether complex salt described above is any one of adimethyl ether ((CH₃)₂O), an ethylmethyl ether (C₂H₅OCH₃), a diethylether ((C₂H₅)₂O), an n-dibutyle ether ((C₄H₉)₂O), and a tetrahydrofuran(C₄H₈O). According to this structure, even in the case of the magnesiumbattery using the electrolytic solution to which any one of thetrifluoroborane-ether complex salts represented by the general formulaBF₃(ether) described above, with regard to the discharge capacity, it ispossible to obtain approximately the same performance. In addition, itis possible to provide the electrolytic solution which can increase thepositive-electrode discharge capacity of the magnesium battery using thenonaqueous electrolytic solution containing therein the magnesium ions.

In addition, it is better to adopt a structure that thetrifluoroborane-ether complex salt described above is added to a ratioof 4.0 mol or less per 1.0 mol of metal magnesium described above.According to this structure, it is possible to provide the electrolyticsolution which can increase the positive-electrode discharge capacity ofthe magnesium battery using the nonaqueous electrolytic solutioncontaining therein the magnesium ions. With the structure that thetrifluoroborane-ether complex salt is added at a ratio of exceeding 4.0mol per 1.0 mol of metal magnesium, the discharge capacity of themagnesium battery is reduced.

In addition, it is better to adopt a structure that the alkyltrifluoromethanesulfonate described above is at least one kind selectedfrom the group consisting of a methyl trifluoromethanesulfonate and anethyl trifluoromethanesulfonate, the alkyl trifluoromethanesulfonatedescribed above is added at a ratio of equal to or more than 0.8 mol andequal to or less than 1.2 mol per 1.0 mol metal magnesium describedabove.

According to this structure, even in the case of the magnesium batteryusing the electrolytic solution manufactured by using any one of thealkyl trifluoromethanesulfonates contained in that group, with regard tothe discharge capacity, it is possible to obtain approximately the sameperformance. In addition, it is possible to provide the electrolyticsolution which can increase the positive-electrode discharge capacity ofthe magnesium battery using the nonaqueous electrolytic solutioncontaining therein the magnesium ions. As the cause for this, it isthought that a stoichiometric proportion of the alkyltrifluoromethanesulfonate to metal magnesium described above in areaction in which a compound similarly to the Grignard reagent iscreated from metal magnesium described above and the alkyltrifluoromethanesulfonate described above is 1. Thus, since there isadopted the structure that the alkyl trifluoromethanesulfonate describedabove is added at the ratio of falling within the range of equal to ormore than 0.8 mol and equal to or less than 1.2 mol per 1.0 mol of metalmagnesium, it is possible to provide the electrolytic solution which canincrease the positive-electrode discharge capacity of the magnesiumbattery using the nonaqueous electrolytic solution containing thereinthe magnesium ions. With the structure that the alkyltrifluoromethanesulfonate described above is added at the ratio of lessthan 0.8 mol and exceeding 1.2 mol per 1.0 mol of metal magnesiumdescribed above, the discharge capacity of the magnesium battery isreduced.

In addition, it is better to adopt a structure that the quaternaryammonium salt described above is at least one kind selected from thegroup consisting of trifluoromethanesulfonic acid tetrabutylammonium(CF₃SO₃N(C₄H₉)₄), trifluoromethanesulfonic acid tributylmethylammonium(CF₃SO₃N(C₄H₉)₃CH₃), trifluoromethanesulfonic acidtriethylmethylammonium (CF₃SO₃N(C₂H₅)₃CH₃), tetrafluoroboric acidtetrabutylammonium (BF₄N(C₄H₉)₄), tetrafluoroboric acidtributylmethylammonium (BF₄N(C₄H₉)₃CH₃), tetrafluoroboric acidtriethylmethylammonium (BF₄N(C₂H₅)₃CH₃),tetrabutylammoniumbis(trifluoromethanesulfonyl)imide((SO₂CF₃)₂N—N(C₄H₉)₄),tributylmethylammoniumbis(trifluoromethanesulfonyl)imide((SO₂CF₃)₂N—N(C₄H₉)₄),tributylmethylammoniumbis(trifluoromethanesulfonyl)imide((SO₂CF₃)₂N—N(C₄H₉)₃CH₃)), andtriethylmethylammoniumbis(trifluoromethanesulfonyl)imide((SO₂CF₃)₂N—N(C₂H₅)₃CH₃), and the 1,3-alkylmethylimidazolium salt is atleast one kind selected from the group consisting of a1,3-dimethylimidazoliumtetrafluoroborate ([(C₃H₃N₂)(CH₃)₂]BF₄), a1-ethyl-3-methylimidazoliumtetrafluoroborate ([C₂H₅(C₃H₃N₂)CH₃]BF₄), a1-butyl-3-methylimidazoliumtetrafluoroborate ([C₄H₉ (C₃H₃N₂)CH₃]BF₄),1,3-dimethylimidazoliumbis(trifluoromethanesulfonyl)imide([(C₃H₃N₂)(CH₃)₂](SO₂CF₃)₂N), 1-ethyl-3-methylimidazoliumbis(trifluoromethanesulfonyl)imide ([C₂H₅(C₃H₃N₂)CH₃](SO₂(CF₃)₂N), and1-butyl-3-methylimidazoliumbis(trifluoromethanesulfonyl)imide ([C₄H₉(C₃H₃N₂)CH₃](SO₂CF₃)₂N).

According to this structure, even in the case of the magnesium batteryusing the electrolytic solution using any one of the quaternary ammoniumsalts of the group described above, or/and any one of the1,3-alkylmethylimidazolium salts of the group described above, withregard to the discharge capacity, it is possible to obtain approximatelythe same performance. In addition, it is possible to provide theelectrolytic solution which can increase the positive-electrodedischarge capacity of the magnesium battery using the nonaqueouselectrolytic solution containing therein the magnesium ions.

In addition, it is better to adopt a structure that either thequaternary ammonium salt described above or the1,3-alkylmethylimidazolium salt described above is added at the ratio ofequal to or more than 1.0 mol and equal to or less than 2.0 mol per 1.0mol of metal magnesium described above, the quaternary ammonium saltdescribed above and the 1,3-alkylmethylimidazolium salt described aboveare added at the ratio of equal to or more than 1.0 mol and equal to orless than 2.0 mol in total per 1.0 mol of metal magnesium describedabove.

According to this structure, it is possible to provide the electrolyticsolution which can increase the positive-electrode discharge capacity ofthe magnesium battery using the nonaqueous electrolytic solutioncontaining therein the magnesium ions. With the structure that eitherthe quaternary ammonium salt described above or the1,3-alkylmethylimidazolium salt described above is added at the ratio ofless than 1.0 mol or exceeding 2.0 mol per 1.0 mol of metal magnesiumdescribed above, the discharge capacity of the magnesium battery isreduced.

In addition, it is better to adopt a structure that the ether systemorganic solvent described above is 1,2-dimethoxyethane. The ether classorganic compound does not form a passive state film during thedissolution and precipitation of magnesium caused by the electrodereaction. In addition, the ether class organic compound can form thecoordinate bond with the magnesium ions, thereby dissolving themagnesium ions. Heretofore, tetrahydrofuran (THF) has been used as theether class organic compound composing the electrolytic solution of themagnesium battery in many cases. However, a boiling point of THF is 66°C. Thus, when the actual use condition of the magnesium battery in thehigh-temperature environment is supposed, it is possible that thetemperature of the magnesium battery becomes higher than the boilingpoint of THF, and it is also possible that the vapor pressure of THFexceeds the atmospheric pressure.

With the magnesium battery using the nonaqueous electrolytic solutioncontaining therein the magnesium ions using 1,2-dimethoxyethane, theboiling point of 1,2-dimethoxyethane is 84° C., and is about 20° C.higher than that of THF. Therefore, the possibility that the temperatureof the magnesium battery becomes higher than the boiling point becomesremarkably small as compared with the case of tetrahydrofuran (THF)which has been conventionally in heavy usage, and the stability in thehigh-temperature environment is enhanced.

In addition, it is better to adopt a structure that metal magnesiumdescribed above is added at the ratio of equal to or more than 0.25mol/l and equal to or less than 1.0 mol/l to the ether system organicsolvent described above. According to this structure, it is possible toprovide the electrolytic solution which can increase thepositive-electrode discharge capacity of the magnesium battery using thenonaqueous electrolytic solution containing therein the magnesium ions.With the structure that metal magnesium described above is added at theratio of less than 0.25 mol/l or exceeding 1.0 mol/l to the ether systemorganic solvent described above, the discharge capacity of the magnesiumbattery is reduced.

In the electrochemical device of the present invention, it is better toadopt a structure that the active material of the first electrodedescribed above is made from either a compound which reacts with themagnesium ion described above or a compound which occludes the magnesiumion described above, and the active material of the second electrodedescribed above is made from either a metal single body of magnesium oran alloy containing therein magnesium. When the electrochemical devicebased on the structure that the metal single body (a pure metal) ofmagnesium is used in the negative electrode is structured as themagnesium battery, it is possible to increase the discharge capacity(energy capacity) of the battery.

Or, when the electrochemical device based on the structure that thealloy containing therein magnesium is used in the negative electrode isstructured as the magnesium battery, for example, the negative electrodecan be stabilized against the repetition of the charge and thedischarge, and so forth. Thus, it is possible to enhance the cyclecharacteristics because the precipitation/dissolution of magnesiumfollowing the charge/discharge is unaccompanied (because magnesium isbrought in as the ions).

It is better to adopt a structure that the first electrode describedabove is a positive electrode including a positive-electrode activematerial made from a graphite fluoride and a positive-electrode mixturecontaining therein copper, and the second electrode described above is anegative electrode containing therein either a magnesium metal or amagnesium alloy as a negative-electrode active material. According tothis structure (first structure), copper is either mixed with thepositive-electrode active material described above, or covered with thepositive-electrode active material described above to be contained inthe positive-electrode mixture described above, and thus contacts thepositive-electrode active material described above, and thepositive-electrode mixture described above contains therein copper.Therefore, it is possible to largely increase the discharge capacity ofthe graphite fluoride, and thus it is possible to provide theelectrochemical device structured as the magnesium battery which has thedischarge capacity corresponding up to about 99% relative to thetheoretical capacity due to one electron reduction reaction.

In addition, it is better to adopt a structure that the first electrodedescribed above is a positive electrode including a positive-electrodemixture containing a positive-electrode active material made from agraphite fluoride, and the second electrode described above is anegative electrode containing therein either a magnesium metal or amagnesium alloy as the negative-electrode active material, and theelectrochemical device has a positive-electrode power collecting bodymade of a conductive material covered with copper or/and copper, or/anda positive-electrode can having an inner surface covered with coppercontacting therein the positive-electrode active material describedabove.

When the positive-electrode power collecting body described above ismade of the conductive material covered with copper or/and copper(second structure), copper contacts the positive-electrode activematerial described above. Thus, it is possible to provide theelectrochemical device structured as the magnesium battery which has thedischarge capacity corresponding to 95.8% relative to the theoreticalcapacity described above without increasing the capacity of the battery.When the inner surface of the positive-electrode can described above iscovered with copper and copper contacts the positive-electrode activematerial described above (third structure), it is possible to providethe magnesium battery which has the discharge capacity corresponding to93.3% relative to the theoretical capacity described above withoutincreasing the capacity of the battery.

In addition, since the inner volume of the battery is not increased, thedischarge capacity per unit volume is prevented from being reduced.Moreover, in the second structure, the positive-electrode powercollecting body covered with copper described above only has to be used.Also, in the third structure, the positive-electrode can having theinner surface coated with copper described above only has to be used.Therefore, the manufacturing cost is prevented from being increasedwithout largely changing the method of manufacturing the battery.

In addition, it is better to adopt a structure that the electrochemicaldevice is structured as the battery. According to this structure, forexample, when the electrochemical device is structured as the magnesiumbattery, the nonaqueous electrolytic solution containing therein themagnesium ions has a sufficiently high oxidation potential, and thus theelectrolyte described above is prevented from being oxidized anddecomposed by a large electromotive force generated between the firstelectrode described above and the second electrode described above.Therefore, it is possible to realize the battery having the large outputvoltage by making full use of the features of magnesium as the metalhaving the large ionization tendency.

In addition, it is better that the electrochemical device is structuredas the secondary battery chargeable by a reverse reaction. According tothis structure, a current is caused to flow in a direction opposite tothat in the case of the discharge, thereby charging the secondarybattery described above, and thus the state of the battery after use canbe returned back to the state before the discharge. Therefore, thesecondary battery can be repetitively used, and thus the resources canbe effectively utilized. Also, even when the battery after the dischargeis charged for reutilization, it is possible to sufficiently make fulluse of the large energy capacity of the magnesium battery. In addition,it is better to adopt a structure that the battery is structured as athin secondary battery. According to this structure, it is possible tostructure the flat and small battery having the small inner capacity.

In the electrochemical device of the present invention, it is better toadopt a structure that copper described above is contained at a massratio of equal to larger than 3 and equal to or smaller than 15 per massratio of 100 of the graphite fluoride in the positive-electrode mixture.According to this structure, the discharge capacity of the graphitefluoride can be increased as compared with the case where no copper iscontained. When the mass ratio of copper is set as 15 relative to thegraphite fluoride described above, the discharge capacity can be largelyincreased without especially increasing the capacity size of thebattery. Thus, it is possible to provide the magnesium battery which hasthe discharge capacity corresponding to about 99% relative to thetheoretical capacity described above.

In addition, it is better to adopt a structure that copper describedabove is contained at least 15 per mass ratio of 100 of the graphitefluoride in the positive-electrode mixture. According to this structure,it is possible to provide the magnesium battery which has the dischargecapacity corresponding to 98.8% relative to the theoretical capacity.When the mass ratio of copper described above is set as being equal toor larger than 15 relative to the mass ratio of the graphite fluoridedescribed above, the discharge capacity per unit volume is preventedfrom being reduced because the discharge capacity is approximatelyconstant and thus copper described above only has to be contained at themass ratio of at least 15.

In addition, it is better to adopt a structure that the electrochemicaldevice has a separator, and the negative-electrode active material isdisposed on one side of the separator, and the positive-electrodemixture is disposed on the other hand of the separator. According tothis structure, the separator described above is made to have a flatsurface shape, whereby the negative-electrode active material and thepositive-electrode mixture can be separated from each other by theseparator, thereby structuring the thin battery. Thus, it is possible tostructure the flat and small battery having the small inner capacity.

A method of manufacturing the nonaqueous electrolytic solutioncontaining therein the magnesium ions according to the present inventionhas the features which will be described below. Thus, it is possible toobtain the nonaqueous electrolytic solution containing therein themagnesium ions which can efficiently bring out the excellentcharacteristics of metal magnesium as the negative-electrode activematerial.

(1) A method of manufacturing the nonaqueous electrolytic solutioncontaining therein the magnesium ions having a first process for addingmetal magnesium, an alkyl trifluoromethanesulfonate (RCF₃SO₃), aquaternary ammonium salt (R¹R²R³R⁴N⁺Z⁻) or/and a 1,3-alkylmethylimidazolium salt ([R(C₃H₃N₂)CH₃]⁺X⁻) to at least an ether systemorganic solvent, and a second process for heating the liquid solutionobtained in the first process, in which the magnesium ions are dissolvedin the ether system organic solvent.

In this regard, R in the general formula RCF₃SO₃ representing alkyltrifluoromethanesulfonate described above, R is either a methyl group oran ethyl group. In addition, each of R¹, R², R³, and R⁴ in the generalformula R¹R²R³R⁴N⁺Z⁻ representing the quaternary ammonium salt describedabove is either an alkyl group or an aryl group, and Z⁻ is any one of achloride ion (Cl⁻), a boromide ion (Br⁻), an iodide ion (I⁻), an aceticacid ion (CH₃COO⁻), a perchloric acid ion (ClO₄ ⁻), a tetrafluoroboricacid ion (BF₄ ⁻), a hexafluorophosphoric acid ion (PF₆ ⁻), ahexafluoroarsenic acid ion (AsF₆ ⁻), a perfluoroalkylsulfonic acid ion(Rf1SO₃ ⁻: Rf1 is a perfluoroalkyl group), and a perfluoroalkylsulfonylimide ion ((Rf2SO₂)₂N⁻: Rf2 is a perfluoroalkyl group).

In addition, R is the general formulas [R(C₃H₃N₂)CH₃]⁺X⁻ representingthe 1,3-alkyl methylimidazolium salt is a methyl group, an ethyl groupor a butyl group, and X⁻ is any one of a tetrafluoroboric acid ion (BF₄⁻) or a bis(trifluoromethanesulfonyl)imide ion ((SO₂CF₃)₂N⁻).

According to the present invention, it is possible to provide the methodof manufacturing the nonaqueous electrolytic solution containing thereinthe magnesium ions in which the magnesium ions are dissolved in theether system organic solvent, and full use of the excellentcharacteristics of metal magnesium as the negative-electrode activematerial can be sufficiently made, and which can be manufactured in thegeneral manufacturing environment such as the dry room.

(2) The method of manufacturing the nonaqueous electrolytic solutioncontaining therein the magnesium ions described in (1) in which in thefirst process described above, an aluminum halide (AlY₃) is added. Inthis regard, Y in the general formula AlY₃ representing the aluminumhalide is any one of chlorine (Cl), bromine (Br), and iodine (I).

According to this structure, it is possible to provide the method ofmanufacturing the electrolyte which can increase a positive-electrodedischarge capacity of the magnesium battery using the nonaqueouselectrolytic solution containing therein the magnesium ions.

(3) The method of manufacturing the nonaqueous electrolytic solutioncontaining therein the magnesium ions described in (2) in which analuminum chloride is used as the aluminum halide.

According to this structure, it is possible to provide the method ofmanufacturing the electrolyte which can increase the positive-electrodedischarge capacity of the magnesium battery using the nonaqueouselectrolyte solution containing therein the magnesium ions.

(4) The method of manufacturing the nonaqueous electrolytic solutioncontaining the magnesium ions described in (2) in which the aluminumhalide is added at a ratio of equal to or less than 1.0 mol per 1.0 molof metal magnesium described above.

According to this structure, it is possible to provide the method ofmanufacturing the electrolytic solution which can increase thepositive-electrode discharge capacity of the magnesium battery using thenonaqueous electrolytic solution containing therein the magnesium ions.With the structure that the aluminum halide is added at the ratio ofexceeding 1.0 mol per 1.0 mol of metal magnesium described above, thedischarge capacity of the magnesium battery is reduced.

(5) The method of manufacturing the nonaqueous electrolytic solutioncontaining therein the magnesium ions described in (1) in which at leastone kind of trifluoroborane-ether complex salt (BF₃(ether)) selectedfrom the group consisting of a trifluoroborane-dimethyl ether complexsalt, a trifluoroborane-ethyl methyl ether complex salt, atrifluoroborane-diethyl ether complex salt, a trifluoroborane-n-dibutylether complex salt, and a trifluoroborane-tetrahydrofuran complex saltis added.

In this regard, Ether in the general formula BF₃(ether) representing thetrifluoroborane-ether complex salt described above is any one of adimethyl ether ((CH₃)₂O), an ethylmethyl ether (C₂H₅OCH₃), a diethylether ((C₂H₅)₂O), an n-dibutyle ether ((C₄H₉)₂O), and a tetrahydrofuran(C₄H₈O).

According to this structure, even in the case of the magnesium batteryusing the electrolytic solution manufactured by using any one of thetrifluoroborane-ether complex salts represented by the general formulaBF₃(ether) described above, with regard to the discharge capacity, it ispossible to obtain approximately the same performance. In addition, itis possible to provide the method of manufacturing the electrolyticsolution which can increase the positive-electrode discharge capacity ofthe magnesium battery using the nonaqueous electrolytic solutioncontaining therein the magnesium ions.

(6) The method of manufacturing the nonaqueous electrolytic solutioncontaining therein the magnesium ions described in (5) in which at leastone kind selected from the group consisting of atrifluoroborane-dimethyl ether complex salt, a trifluoroborane-ethylmethyl ether complex salt, a trifluoroborane-diethyl ether complex salt,a trifluoroborane-n-dibutyl ether complex salt, and atrifluoroborane-tetrahydrofuran complex salt is used as thetrifluoroborane-ether complex salt described above.

According to this structure, even in the case of the magnesium batteryusing the electrolytic solution manufactured by using any of thetrifluoroborane-ether complex salts represented by the general formulaBF₃(ether) described above, with regard to the discharge capacity, it ispossible to obtain approximately the same performance. In addition, itis possible to provide the method of manufacturing the electrolyticsolution which can increase the positive-electrode discharge capacity ofthe magnesium battery using the nonaqueous electrolytic solutioncontaining therein the magnesium ions.

(7) The method of manufacturing the nonaqueous electrolytic solutioncontaining therein the magnesium ions described in (5) in which thetrifluoroborane-ether complex salt described above is added at a ratioof equal to or less than 0.4 mol per 1.0 mol of metal magnesiumdescribed above.

According to this structure, it is possible to provide the method ofmanufacturing the electrolytic solution which can increase thepositive-electrode discharge capacity of the magnesium battery using thenonaqueous electrolytic solution containing therein the magnesium ions.With the structure that the trifluoroborane-ether complex salt describedabove is added at the ratio of exceeding 0.4 mol per 1.0 mol of metalmagnesium described above, the discharge capacity of the magnesiumbattery is reduced.

(8) The method of manufacturing the nonaqueous electrolytic solutioncontaining the magnesium ions described in (1) in which at least onekind selected from the group consisting of a methyltrifluoromethanesulfonate (CH₃CF₃SO₃) and an ethyltrifluoromethanesulfonate (C₂H₅CF₃SO₃) is used as the alkyltrifluoromethanesulfonate.

According to this structure, even in the case of the magnesium batteryusing the electrolytic solution manufactured by using any of the alkyltrifluoromethanesulfonates in the group described above, with regard tothe discharge capacity, it is possible to obtain approximately the sameperformance. In addition, it is possible to provide the method ofmanufacturing the electrolytic solution which can increase thepositive-electrode discharge capacity of the magnesium battery using thenonaqueous electrolytic solution containing therein the magnesium ions.

(9) The method of manufacturing the nonaqueous electrolytic solutioncontaining therein the magnesium ions described in (1) in which thealkyl trifluoromethanesulfonate is added at a ratio of equal to or morethan 0.8 mol and equal to or less than 1.2 mol per 1.0 mol of metalmagnesium described above.

As the cause for this, it is thought that a stoichiometric proportion ofthe alkyl trifluoromethanesulfonate to metal magnesium described abovein a reaction in which a compound similar to the Grignard reagent iscreated from metal magnesium described above and the alkyltrifluoromethanesulfonate described above is 1. Thus, since there isadopted the structure that the alkyl trifluoromethanesulfonate describedabove is added at the ratio of falling within the range of equal to ormore than 0.8 mol and equal to or less than 1.2 mol per 1.0 mol of metalmagnesium described above, it is possible to provide the method ofmanufacturing the electrolytic solution which can increase thepositive-electrode discharge capacity of the magnesium battery using thenonaqueous electrolytic solution containing therein the magnesium ions.

With the structure that the alkyl trifluoromethanesulfonate describedabove is added at the ratio of less than 0.8 mol, or exceeding 1.2 molper 1.0 mol of metal magnesium described above, the discharge capacityof the magnesium battery is reduced.

(10) The method of manufacturing the nonaqueous electrolytic solutioncontaining therein the magnesium ions described in (1) in which thequaternary ammonium salt described above is at least one kind selectedfrom the group consisting of trifluoromethanesulfonic acidtetrabutylammonium, trifluoromethanesulfonic acidtributylmethylammonium, trifluoromethanesulfonic acidtriethylmethylammonium, tetrafluoroboric acid tetrabutylammonium,tetrafluoroboric acid tributylmethylammonium, tetrafluoroboric acidtriethylmethylammonium,tetrabutylammoniumbis(trifluoromethanesulfonyl)imide,triethylmethylammoniumbis(trifluoromethanesulfonyl)imide, andtriethylmethylammoniumbis(trifluoromethanesulfonyl)imide, and the1,3-alkylmethylimidazolium salt is at least one kind selected from thegroup consisting of a 1,3-dimethylimidazoliumtetrafluoroborate, a1-ethyl-3-methylimidazoliumtetrafluoroborate, a1-butyl-3-methylimidazoliumtetrafluoroborate,1,3-dimethylimidazoliumbis(trifluoromethanesulfonyl)imide,1-ethyl-3-methylimidazoliumbis(trifluoromethanesulfonyl)imide, and1-butyl-3-methylimidazoliumbis(trifluoromethanesulfonyl)imide.

According to this structure, even in the case of the magnesium batteryusing the electrolytic solution manufactured by using any one of thequaternary ammonium salts of the group described above, or any one ofthe 1,3-alkylmethylimidazolium salts of the group described above, withregard to the discharge capacity, it is possible to obtain approximatelythe same performance. In addition, it is possible to provide the methodof manufacturing the electrolytic solution which can increase thepositive-electrode discharge capacity of the magnesium battery using thenonaqueous electrolytic solution containing therein the magnesium ions.

(11) The method of manufacturing the nonaqueous electrolytic solutioncontaining the magnesium ions described in (1) in which either thequaternary ammonium salt described above or the1,3-alkylmethylimidazolium salt described above is added at the ratio ofequal to or more than 1.0 mol and equal to or less than 2.0 mol per 1.0mol of metal magnesium described above, or the quaternary ammonium saltdescribed above and the 1,3-alkylmethylimidazolium salt described aboveare added at the ratio of equal to or more than 1.0 mol and equal to orless than 2.0 mol in total per 1.0 mol of metal magnesium describedabove.

According to this structure, it is possible to provide the method ofmanufacturing the electrolytic solution which can increase thepositive-electrode discharge capacity of the magnesium battery using thenonaqueous electrolytic solution containing therein the magnesium ions.With the structure that either the quaternary ammonium salt describedabove or the 1,3-alkylmethylimidazolium salt described above is added atthe ratio of less than 1.0 mol or exceeding 2.0 mol per 1.0 mol of metalmagnesium described above, the discharge capacity of the magnesiumbattery is reduced.

(12) The method of manufacturing the nonaqueous electrolytic solutioncontaining therein the magnesium ions described in (1) in which1,2-dimethoxyethane is used as the ether system organic solventdescribed above.

The ether class organic compound does not form a passive state filmduring the dissolution and precipitation of magnesium caused by theelectrode reaction. In addition, the ether class organic compound canform the coordinate bond with the magnesium ions, thereby dissolving themagnesium ions. Heretofore, tetrahydrofuran (THF) has been used as theether class organic compound composing the electrolytic solution of themagnesium battery in many cases. However, a boiling point of THF is 66°C. Thus, when the actual use condition of the magnesium battery in thehigh-temperature environment is supposed, it is possible that thetemperature of the magnesium battery becomes higher than the boilingpoint of THF, and it is also possible that the vapor pressure of THFexceeds the atmospheric pressure.

With the magnesium battery using the nonaqueous electrolytic solutioncontaining therein the magnesium ions using 1,2-dimethoxyethane, theboiling point of 1,2-dimethoxyethane is 84° C., and is about 20° C.higher than that of THF. Therefore, the possibility that the temperatureof the magnesium battery becomes higher than the boiling point becomesremarkably small as compared with the case of tetrahydrofuran which hasbeen conventionally in heavy usage, and the stability at thehigh-temperature environment is enhanced.

(13) The method of manufacturing the nonaqueous electrolytic solutioncontaining therein the magnesium ions described in (1) in which metalmagnesium described above is added at the ratio of equal to or more than0.25 mol/l and equal to or less than 1.0 mol/l to the ether systemorganic solvent described above.

According to this structure, it is possible to provide the method ofmanufacturing the electrolytic solution which can increase thepositive-electrode discharge capacity of the magnesium battery using thenonaqueous electrolytic solution containing therein the magnesium ions.With the structure that metal magnesium described above is added at theratio of less than 0.25 mol/l or exceeding 1.0 mol/l to the ether systemorganic solvent described above, the discharge capacity of the magnesiumbattery is reduced.

(14) The method of manufacturing the nonaqueous electrolytic solutioncontaining therein the magnesium ions described in (1) in which in thesecond process described above, a heating temperature of the liquidsolution described above is set as being equal to or higher than 50° C.and equal to or lower than 80° C.

According to this structure, it is possible to provide the method ofmanufacturing the electrolytic solution which can increase thepositive-electrode discharge capacity of the magnesium battery using thenonaqueous electrolytic solution containing therein the magnesium ions.With the structure that the heating temperature of the liquid solutiondescribed above is lower than 50° C. or exceeding 80° C., the dischargecapacity of the magnesium battery is reduced.

The inventor of this application has examined the electrochemicalcharacteristics of the various kinds of nonaqueous electrolyticsolutions each containing therein the magnesium ions, and stability inthe atmosphere including the stability during the manufacturing processin detail. As a result, it has become clear that the following method issuitable as the method of manufacturing the electrolytic solution of themagnesium battery.

The magnesium battery has a positive-electrode pellet composed of apositive-electrode can, a positive-electrode pellet made of apositive-electrode active material and the like, a positive electrodecomposed of a metallic net-like body (metallic net supporting body) madefrom a metallic net, a negative electrode composed of anegative-electrode cap and a negative-electrode active material, and aseparator the inside of which is impregnated with the nonaqueouselectrolyte solution containing therein the magnesium ions, and disposedbetween the positive-electrode pellet and the negative-electrode activematerial.

Metal magnesium, the alkyl trifluoromethanesulfonate, the quaternaryammonium salt or/and the 1,3-alkylmethylimidazolium salt, morepreferably, an aluminum halide are added to the ether system organicsolvent, and a heating treatment is carried out while they are stirred.After that, furthermore preferably, the trifluoroborane-ether complexsalt is added thereto, thereby making it possible to manufacture thenonaqueous electrolytic solution containing therein the magnesium ionsin the general manufacturing environment such as the dry room. It isnoted that either a pure solvent or a mixed solvent containing thereinat least one kind of ether class organic compound can be used as theether system organic solvent.

The magnesium battery as the electrochemical device which has thenonaqueous electrolytic solution containing therein the magnesium ions,the positive electrode, and the negative electrode, and which isstructured in such a way that the negative-electrode active material isoxidized to generate the magnesium ions can sufficiently bring out theexcellent characteristics of metal magnesium and shows the largedischarge capacity.

In addition, in the magnesium battery of the present invention, at leastone or more of the structure that copper and the positive-electrodeactive material contact each other, that is, the structure that copperis contained in the positive-electrode mixture, the structure that thepositive-electrode power collecting body is made of either copper or amaterial covered with copper, and the structure that the inner surfaceof the positive-electrode can is covered with copper are adopted,thereby making it possible to realize the magnesium battery having thelarge discharge capacity.

Hereinafter, an embodiment according to the present invention will bedescribed in detail with reference to the accompanying drawings.

EMBODIMENT

In this embodiment, a description will now be given with respect to thenonaqueous electrolytic liquid containing therein the magnesium ionsbased on the present invention, and the magnesium battery as an exampleof the electrochemical device using the nonaqueous electrolytic liquid.In this connection, it is noticed in advance that the description givenherein is merely an example, and thus the present invention is by nomeans limited thereto. Although hereinafter, a coin type (referred to asa button type as well) battery will be described, the present inventioncan also be applied to a cylinder type or square type battery having aspiral structure in its inside in which a thin positive electrode and athin negative electrode between which a separator is held are wound intoa spiral-like shape, and thus the same effects as those in the coin typebattery can be obtained.

FIG. 1 is a cross sectional view showing a structure of a magnesiumbattery 10 in the embodiment of the present invention.

As shown in FIG. 1, the magnesium battery 10 is formed as a coin typebattery having a thin disc-like external form shape. A positiveelectrode 11 as a first electrode is composed of a positive-electrodecan 1, a positive-electrode pellet 2, and a metallic net-like body 3(hereinafter referred to as a metallic net supporting body 3 as well)formed from a metallic net, and a negative electrode 12 as a secondelectrode is composed of a negative-electrode cup 4 and anegative-electrode active material 5. The positive-electrode pellet 2and the negative-electrode active material 5 are disposed in such a waythat the positive-electrode pellet 2 and the negative-electrode activematerial 5 each contact the separator 6, and thus the positive-electrodepellet 2 and the negative-electrode active material 5 are prevented frombeing mutually short-circuited by the separator 6. Also, the separator 6is impregnated with the electrolytic solution, and thus the electrolyticsolution is infused into the separator 6.

The positive-electrode pellet 2 into which the positive-electrodemixture composed of the positive-electrode active material, theconductive agent and the binder are pressed together with the metallicnet-like body 3 so as to have a disc-like shape is disposed inside thepositive-electrode can 1, the porous separator 6 is provided on thepositive-electrode pellet 2, and thus is impregnated with theelectrolytic solution 7. Subsequently, the negative-electrode activematerial 5 obtained by carrying out the press-molding so as to have adisc-like shape similarly to the case of the positive-electrode pellet 2is placed on the separator 6, and the negative-electrode cup 4 and thepositive-electrode can 1 are fitted into each other through a sealinggasket 8, thereby forming the hermetically-sealed coin type battery.

The positive-electrode can 1 functions as an external positive electrodeterminal of a power collecting body and the battery. Thepositive-electrode mixture composed of the positive-electrode activematerial, the conductive agent and the binder are press-molded togetherwith the metallic net-like body 3 into the positive-electrode pellet 2so as to have the disc-like shape, and the positive-electrode pellet 2is disposed inside the positive electrode can 1. The metallic netsupporting body 3 functions as the supporting body and the powercollecting body (positive-electrode power collecting body) for thepositive-electrode pellet 2.

The positive-electrode active material, for example, is made of anoxide, a halide or the like of a metal element such as scandium (Sc),titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe),cobalt (Co), nickel (Ni), copper (Cu) or zinc (Zn) in addition to agraphite fluoride ((CF)_(n)).

A graphite class, a conductive fiber class such as a carbon fiber or ametallic fiber, metallic powder, a conductive whisker, a conductivemetallic oxide, an organic conductive material, or the like, forexample, is used as the conductive agent.

A polymer material containing therein fluorine such as a vinylidenefluoride (PVdF), hexafluoropropylene (HFP), or chlorotrifluoroethylene(CTFE), tetrafluoroethylene (PTFE), or a copolymer of these polymermaterials, for example, a copolymer of the vinylidene fluoride andhexafluoropropylene, or the like, for example, is used as the binder.

The negative-electrode cup 4 functions as an external negative-electrodeterminal of the power collecting body (negative-electrode powercollecting body) and the battery. The negative-electrode active material5, for example, is a metal magnesium plate which is molded so as to havea disc-like shape, and is disposed so as to contact thenegative-electrode cup 4. For the purpose of increasing the energycapacity of the negative electrode 12 as much as possible, pure metalmagnesium is desirably used in the negative-electrode active material 5.However, for the purpose of enhancing the battery performance other thanthe energy capacity such as stabilizing the negative-electrode activematerial 5 against the repetition of the charge and discharge, an alloycan also be used as the material of the negative-electrode activematerial 5.

A polyolefin system fine-porous film or the like such as polypropyleneor polyethylene can be used in the separator 6. The positive-electrodecan 1 and the negative-electrode cup 4 are fitted to each other throughthe sealing gasket 8. The sealing gasket 8 serves to hermetically sealthe inside of the magnesium battery 10 while the positive electrode 11and the negative electrode 12 are electrically insulated from eachother.

The electrolytic solution 7 is a nonaqueous electrolytic solutioncontaining therein the magnesium ions based on the present invention. Inthe first preparation example for the manufacturing of the electrolyticsolution, 1,2-dimethoxyethane is used as the ether system organicsolvent, metal magnesium is added at a ratio of 0.25 mol/l (liter)˜1.0mol/l to this solvent. Also, methy trifluoromethanesulfonate is used asan alkyl trifluoromethanesulfonate and is added at a ratio of 0.8mol˜1.2 mol per 1.0 mol of magnesium. Also, tetrafluoroboric acidtetrabutylammonium is used as a quaternary ammonium salt and is added ata ratio of 1.0 mol˜2.0 mol per 1.0 mol of magnesium. More preferably, analuminum chloride is used an aluminum halide and is added at a ratio of1.0 mol per 1.0 mol of magnesium. A heating treatment is carried out at50° C.˜80° C. while they are stirred, thereby dissolving both themagnesium ions and the aluminum ions in 1,2-dimethoxyethane as the ethersystem organic solvent.

It is noted that the concentration of 0.25 mol/l˜1.0 mol/l, and thetemperature of 50° C.˜80° C. mean a concentration range of equal to ormore than 0.25 mol/l and equal to or less than 1.0 mol/l, and atemperature range of equal to or higher than 50° C. and equal to orlower than 80° C., respectively, and in the following description, themark “˜” representing a range represents a range including numericalvalues on both sides of the mark.

More preferably, after that, a trifluoroborane-dimethylether complexsalt is added at a ratio of 4.0 mol or less per 1.0 mol of metalmagnesium.

In a second preparation example for the manufacturing of the nonaqueouselectrolytic solution containing therein the magnesium ions based on thepresent invention, 1,2-dimethoxyethane is used as the ether systemorganic solvent and metal magnesium is added at a ratio of 0.25mol/l˜1.0 mol/l to this solvent. Also, a methyltrifluoromethanesulfonate is used as an alkyl trifluoromethanesulfonateand is added at a ratio of 0.8 mol˜1.2 mol per 1.0 mol of magnesium.1-ethyl-3-methylimidazoliumbis(trifluoromethanesulfonyl)imide is used asa 1,3-alkylmethylimidazolium salt and is added at a ratio of 1.0 mol˜2.0mol per 1.0 mol of magnesium. More preferably, aluminum chloride is usedan aluminum halide and is added at a ratio of 1.0 mol per 1.0 mol ofmagnesium. A heating treatment is carried out at 50° C.˜80° C. whilethey are stirred, thereby dissolving both the magnesium ions and thealuminum ions in 1,2-dimethylethane as the ether system organic solvent.

More preferably, after that, a trifluoroborane-diethylether complex saltis added at a ratio of 4.0 mol or less per 1.0 mol of metal magnesium.

Although the quaternary ammonium salt and the 1,3-alkylmethylimidazoliumsalt are used in the first preparation example and the secondpreparation example which have been described so far, respectively, thequaternary ammonium salt and the 1,3-alkylmethylimidazolium salt may beused at the same time (third preparation example). The quaternaryammonium salt and the 1,3-alkylmethylimidazolium salt are used at thesame time instead of using the quaternary ammonium salt in the firstpreparation example, or the 1,3-alkylmethylimidazolium salt in thesecond preparation example, and are added at a ratio of 1.0 mol˜2.0 molin total per 1.0 mol of magnesium, and the nonaqueous electrolyticsolution is prepared similarly to each of the cases of the first exampleand the second example, thereby making it possible to manufacture thenonaqueous electrolytic solution having the same performance as that ofeach of the first example and the second example.

In the magnesium battery of the present invention, as will be describedsubsequently, it is possible to adopt a structure that copper and thepositive-electrode active material contact each other. (1) Thepositive-electrode mixture composed of the positive-electrode activematerial, the conductive agent, and the binder is mixed with the copperpowder, or the positive-electrode active material is covered with copperto contain copper in the positive-electrode active material, and copperis used in a state of contacting the positive-electrode active material.(2) The conductive material covered with copper, or/and thepositive-electrode power collecting body made of copper are used, andcopper is used in a state of contacting the positive-electrode activematerial. (3) The positive-electrode can having the inner surfacecovered with copper is used, and copper is used in a state of contactingthe positive-electrode active material. Copper is used in the threeforms, and the structure that copper and the positive-electrode activematerial contact each other is adopted, whereby it is possible toefficiently develop the discharge performance of the graphite fluorideas the positive-electrode active material, and it is possible to largelyincrease the discharge capacity.

When the positive-electrode active material has such a structure as tocontact copper, the three forms described above can be applied to thecoin type (referred to as the button type as well) battery, the cylindertype battery, the square type battery or the like having the spiralstructure in its inside in which the thin positive electrode and thethin negative electrode between which the separator is held are woundinto the spiral shape, and thus the same effects as those in the cointype battery can be obtained. It is noted that one or more forms of thethree forms described above are adopted, thereby making also it possibleto form the battery.

In the battery using the form (1) described above, that is, in thebattery having the structure that copper is contained in thepositive-electrode mixture, when the mass ratio of copper to thegraphite fluoride in the positive-electrode mixture, that is, the ratiorepresented by (mass of copper/mass of graphite fluoride)×100 is 8.5,10.0, 12.3, 15.0, it is possible to realize the battery having thedischarge capacity of 70%, 80%, 90%, 98.8% of the theoretical capacity(about 860 mAh/g). When copper is contained at the mass ratio of atleast 15 per 100 of the mass ratio of the graphite fluoride, it ispossible to realize the magnesium battery having the discharge capacitycorresponding to about 99% of the theoretical capacity.

In the negative electrode 12 of the magnesium battery 10, during thedischarge, metal magnesium as the negative-electrode active material 5,or an alloy of metal magnesium is oxidized in accordance with thefollowing reaction formula, and the electrons are discharged to anexternal circuit through the negative-electrode cup 4:

Negative electrode: Mg→Mg²⁺+2e ⁻

It is thought that the magnesium ions generated in this reaction aredissolved in the electrolytic solution 7, and are diffused in theelectrolytic solution 7 to be moved to the positive electrode 11 side.

It is thought that the magnesium ions which have been moved to thepositive electrode 11 are trapped on a surface of either the oxide orthe halide as the positive-electrode active material, or inner wallsurfaces within holes formed either in the oxide or in the halide toreact with the positive-electrode active material. At this time, theelements composing the positive-electrode active material are reduced,and the electrons are taken in from the external circuit through thepositive-electrode can 1 or the like.

The magnesium battery according to the present invention can be used asa power source of an apparatus which is fixed to and installed in afactory or a home, a power source used in a portable and transportableinformation apparatus such as a telephone or a PC, or a power sourcemounted to a mobile apparatus such as an auto mobile.

Hereinafter, Examples based on the present invention will be described.

EXAMPLES Example 1

In Example 1, the coin type magnesium battery 10 shown in FIG. 1 wasmanufactured by using metal magnesium as the negative-electrode activematerial 5, by using the manganese oxide as the positive-electrodeactive material, and by using the electrolytic solution based on thepresent invention, and the performance of the electrolytic solution wasexamined.

<Synthesis of Nonelectrolytic Solution 7 Containing Magnesium Ions>

0.12 g of metal magnesium was added to 10 ml of 1,2-dimethoxyethane. Inaddition, 0.55 ml of a methyl trifluoromethanesulfonate (MeTFS), 2.47 gof tetrafluoroboric acid tetrabutylammonium (TBABF₄), and 0.33 g of analuminum chloride (AlCl₃) were added. This corresponds that metalmagnesium, a methyl trifluoromethanesulfonate, tetrafluoroboric acidtetrabutylammonium, and an aluminum chloride are added at the ratio of0.50 mol/l, at the ratio of 0.50 mol/l, at the ratio of 0.75 mol/l, andat the ratio of 0.25 mol/l to 1,2-dimethoxyethane, respectively. Aheating treatment was carried out at 60° C. for 20 hours while they werestirred, thereby dissolving both the magnesium ions and the aluminumions in 1,2-dimethoxyethane.

After that, 1.26 ml/of a trifluoroborane-diethylether complex salt(BF₃DEE) was added, and was then sufficiently stirred. This correspondsto that a trifluoroborane-diethylether complex salt is added at theratio of 1.00 mol/l.

<Formation of Positive-Electrode Pellet 2 and Negative-Electrode ActiveMetal 5>

Firstly, after 2 g of potassium permanganate was added to 50 ml of ahydrochloric acid having a concentration of 4 mol/l, was stirred at roomtemperature for 15 minutes, and was stationarily left. Then, after aresulting precipitate was filtered out and was then sufficiently rinsedin water, a heating treatment was carried out at 300° C. for two hours,thereby synthesizing a manganese oxide.

Next, the manganese oxide described above, graphite as the coordinateagent, and a poly(vinylidene fluoride) (PVdF) as the binder were mixedat a mass ratio of 78:20:2 with each other. N-methylpyrrolidone (NMP)was added as the solvent to the mixture, poly(vinylidene fluoride) asthe binder was dissolved in the mixture, and both a manganese oxide andgraphite were dissolved in the resulting liquid solution, therebyobtaining a positive-electrode mixture slurry. A heating treatment wascarried out for the resulting slurry at 120° C. for two hours, and thusNMP was vaporized from the slurry to solidify the slurry. The resultingsolidified material was pounded into powder in a mortar, therebyobtaining the positive-electrode mixture.

0.1 g of the positive-electrode mixture was weighed, and was thermallycompressed to the metallic net supporting body 3 made of nickel at apredetermined pressure to be pressure-molded into a disc-like shape,thereby forming the positive-electrode pellet 2 which was 15.5 mm indiameter and was 250 μm in thickness.

On the other hand, a magnesium plate was pressed to be pressure-moldedinto a disc-like shape which was 15.5 mm in diameter and was 800 μm inthickness, thereby forming the negative-electrode active material 5.

<Manufacture of Magnesium Battery 10>

The magnesium battery 10 was assembled in the dry room. Firstly, afterthe positive-electrode pellet 2 was disposed inside thepositive-electrode can 1, and the separator 6 made from a fine-porousfilm made of polyethylene and having a thickness of 25 μm was disposedon the positive-electrode pellet 2, the separator 6 was impregnated witha given amount of the electrolytic liquid 7 to infuse the electrolyticliquid 7 into the separator 6. Next, the magnesium plate as thenegative-electrode active material 5 was piled on the separator 6, andthe sealing gasket 8 and the negative-electrode cup 4 were disposed inpredetermined positions, respectively. Finally, the positive-electrodecan 1 and the negative-electrode cup 4 were fitted into each otherthrough the sealing gasket 8, thereby manufacturing the coin typemagnesium battery 10 which was 20 mm in outer diameter, and was 1.6 mmin height.

<Discharge Test>

A discharge test was carried out for the magnesium battery 10 of Example1 manufactured in the manner as described above with a constant currentof 0.5 mA until the battery voltage became 0.2 V.

FIG. 2 is a diagram showing a relationship among concentrations of Mg,MeTFS, TBABF₄, AlCl₃, and BF₃DEE used in the synthesis of theelectrolytic solution, the heating temperature, and the dischargecapacity of the magnesium battery using the synthesized electrolyticsolution in Example 1 of the present invention, and Comparative Example1 to Example 6, Comparative Example 7-1, and Comparative Example 7-2which will be described later.

In FIG. 2, and FIG. 3 to FIG. 8 which will be described later, the MeTFSconcentration means the concentration of a methyltrifluoromethanesulfonate, the TBABF₄ concentration means theconcentration of tetrafluoroboric acid tetrabutylammonium, and theBF₃DEE concentration means the concentration of thetrifluoroborane-diethylether complex salt.

It is noted that since an excessive amount of metal magnesium is used asthe negative-electrode active material 5, the discharge capacityobtained herein can be regarded as being determined by the dischargecapacity of the positive-electrode active material, and the performanceof the electrolytic solution.

Comparative Examples 1 to 6

In Comparative Examples 1 to 6, the influence of presence or absence oftetrafluoroboric acid tetrabutylammonium, an aluminum chloride, and thetrifluoroborane-diethylether complex salt which were used during themanufacture of the electrolytic solution 7 was checked. The magnesiumbattery having the same structure as that of the magnesium battery 10shown in FIG. 1 was manufactured similarly to the case of Example 1except for presence or absence thereof, and the discharge test wascarried out about that magnesium battery.

As a result, in each of Comparative Example 2, Comparative Example 3,and Comparative Example 6 each using the electrolytic solution not usingtetrafluoroboric acid tetrabutylammonium, the discharge capacity was notobtained at all, or only the very small discharge capacity was obtained.In addition, in each of Comparative Example 1, Comparative Example 4,and Comparative Example 5 each using the electrolytic solution usingtetrafluoroboric acid tetrabutylammonium, the large discharge capacitywas obtained, but a value of the discharge capacity thus obtained wassmaller than that in Example 1.

Comparative Example 7

In Comparative Example 7, a THF solution (having a concentration of 0.25mol/l) of magnesium dichlorobutylethylaluminate (Mg[AlCl₂(C₂H₅)(C₄H₉)₂]described as the electrolytic solution for the magnesium battery in theNon-Patent Document 1 was used as the electrolytic solution instead ofusing the electrolytic solution based on the present invention. Amagnesium battery having the same structure as that of the magnesiumbattery 10 was manufactured similarly to the case of Example 1 exceptfor this THF solution. In this case, in Comparative Example 7-1, themagnesium battery was assembled within the dry room similarly to thecase of Example 1. On the other hand, in Comparative Example 7-2, themagnesium battery was assembled in an inactive gas ambient atmospherewithin an argon gloved box.

Although the discharge test was carried out about each of thesemagnesium batteries similarly to the case of Example 1, the dischargecapacity was not obtained at all in Comparative Example 7-1. Thedischarge capacity obtained in the battery of Comparative Example 7-2 isshown in FIG. 2.

In each of the batteries of Comparative Example 2, Comparative Example3, and Comparative Example 6, the discharge capacity was not obtained,or was very small. From this, it is understood that tetrafluoroboricacid tetrabutylammonium as the quaternary ammonium salt is an essentialcomponent in the electrolytic solution based on the present invention.In addition, the effective discharge capacity was not obtained in thebattery of Comparative Example 7-1. From this, equipment with which themagnesium battery can be assembled in the inactive gas ambientatmosphere such as the argon gloved box is necessary for using magnesiumdichlorobutylethylaluminate described in the Non-Patent Document 1.

On the other hand, the batteries of Example 1, Comparative Example 1,Comparative Example 4, Comparative Example 5, and Comparative Example7-2 showed approximately the equivalent discharge capacities. From aresult in Example 5 which will be described later, it is thought thatthese discharge capacities were mainly determined by the dischargecapacity of the positive-electrode active material, and the electrolyticsolution exercised its function without a problem. Therefore, in each ofbatteries of Examples which will be described below, when the dischargecapacity approximately compatible either to that of the battery ofExample 1, or to that of each of the batteries of Comparative Example 1,Comparative Example 4, Comparative Example 5, and Comparative Example7-2 was obtained, the electrolytic solution of the battery concerned wasjudged to be favorable.

Next, a synthesis condition under which the electrolytic solution basedon the present invention was favorable in terms of the electrolyticsolution of the magnesium battery was examined in Example 2 to Example6.

Example 2

In Example 2, the concentration of the methyl trifluoromethanesulfonatewas changed in the range of 0 mol/l˜0.80 mol/l, and thus theelectrolytic solution was prepared. The magnesium battery 10 using theelectrolytic solution was manufactured similarly to the case of Example1 except for this respect, and the discharge test was carried out aboutthe magnesium battery 10.

FIG. 3 is a diagram showing a relationship among the concentrations ofMg, MeTFS, TBABF₄, AlCl₃, and BF₃DEE used in the synthesis of theelectrolytic solution, the heating temperature, and the dischargecapacity of the magnesium battery using the synthesized electrolyticsolution in Comparative Example 2-1, Example 2-1 to Example 2-7, andExample 1 of the present invention.

(A) of FIG. 3 is a numerical table showing the concentrations, heatingtemperature and discharge capacity described above, and (B) of FIG. 3 isa diagram in which the discharge capacity shown in (A) of FIG. 3 isexpressed in the form of a graph. In (A) and (B) of FIG. 3, an axis ofordinate represents the discharge capacity (mAh/g) of thepositive-electrode active material, and an axis of abscissa representsthe MeTFS concentration (mol/l).

(B) of FIG. 3 is a graph showing a relationship between theconcentration of the methyl trifluoromethane sulfonate used in thesynthesis of the electrolytic solution in Example 2, and the dischargecapacity of the magnesium battery. As can be seen from FIG. 3, when theconcentration of the methyl trifluoromethanesulfonate is in the range of0.40 mol/l˜0.60 mol/l (an additive amount of methyltrifluoromethanesulfonate is in the range of 0.80 mol˜1.20 mol per 1.00mol of Mg), the electrolytic solution synthesized in Example 2 isfavorable in terms of the electrolytic solution of the magnesium battery10.

Example 3

In Example 3, the concentration of tetrafluoroboric acidtetrabutylammonium was changed in the range of 0 mol/l˜1.20 mol/l, andthus the electrolytic solution was prepared. The magnesium battery 10was manufactured similarly to the case of Example 1 except for thisrespect, and the discharge test was carried out about the magnesiumbattery 10.

FIG. 4 is a diagram showing a relationship among the concentrations ofMg, MeTFS, TBABF₄, AlCl₃, and BF₃DEE used in the synthesis of theelectrolytic solution, the heating temperature, and the dischargecapacity of the magnesium battery using the synthesized electrolyticsolution in Comparative Example 3-1, Example 3-1 to Example 3-6, andExample 1 of the present invention.

(A) of FIG. 4 is a numerical table showing the concentrations, heatingtemperature and discharge capacity described above, and (B) of FIG. 4 isa diagram in which the discharge capacity shown in (A) of FIG. 4 isexpressed in the form of a graph. In (A) and (B) of FIG. 4, an axis ofordinate represents the discharge capacity (mAh/g) of thepositive-electrode active material, and an axis of abscissa representsthe TBABF₄ concentration (mol/l).

(B) of FIG. 4 is a graph showing a relationship between theconcentration of tetrafluoroboric acid tetrabutylammonium used in thesynthesis of the electrolytic solution in Example 3, and the dischargecapacity of the magnesium battery. As can be seen from FIG. 4, when theconcentration of tetrafluoroboric acid tetrabutylammonium is in therange of 0.50 mol/l˜1.00 mol/l (an additive amount of tetrafluoroboricacid tetrabutylammonium is in the range of 1.00 mol˜2.00 mol per 1.00mol of Mg), the electrolytic solution synthesized in Example 3 isfavorable in terms of the electrolytic solution of the magnesium battery10.

Example 4

In Example 4, the concentration of an aluminum chloride was changed inthe range of 0 mol/l˜1.00 mol/l, and thus the electrolytic solution wasprepared. The magnesium battery 10 was manufactured similarly to thecase of Example 1 except for this respect, and the discharge test wascarried out about the magnesium battery 10.

FIG. 5 is a diagram showing a relationship among the concentration ofMg, MeTFS, TBABF₄, AlCl₃, and BF₃DEE used in the synthesis of theelectrolytic solution, the heating temperature, and the dischargecapacity of the magnesium battery using the synthesized electrolyticsolution in Example 4-1 to Example 4-7, and Example 1 of the presentinvention.

(A) of FIG. 5 is a numeral table showing the concentrations, heatingtemperatures and discharge capacity described above, and (B) of FIG. 5is a diagram in which the discharge capacity shown in (A) of FIG. 5 isexpressed in the form of a graph. In (A) and (B) of FIG. 5, an axis ofordinate represents the discharge capacity (mAh/g) of thepositive-electrode active material, and an axis of abscissa representsthe AlCl₃ concentration (mol/l).

(B) of FIG. 5 is a graph showing a relationship between theconcentration of the aluminum chloride used in the synthesis of theelectrolytic solution in Example 4, and the discharge capacity of themagnesium battery. As can been from FIG. 5, when the concentration ofthe aluminum chloride is equal to or less than 0.50 mol/l (an additiveamount of aluminum chloride is equal to or less than 1.00 mol per 1.00mol of Mg), the electrolytic solution synthesized in Example 4 isfavorable in terms of the electrolytic solution of the magnesium battery10.

Example 5

In Example 5, the concentration of magnesium was changed in the range of0.10 mol/l˜1.50 mol/l, and thus the electrolytic solution was prepared.In this case, the electrolytic solution was prepared in such a way thateach of the concentrations of the methyl trifluoromethanesulfonate andthe aluminum chloride was made equal to that of Mg, and each of theconcentrations of tetrafluoroboric acid tetrabutylammonium and thetrifluoroborane-diethylether complex salt became twice that ofmagnesium. The magnesium battery 10 was manufactured similarly to thecase of Example 1 except for this respect, and the discharge test wascarried out about the magnesium battery 10.

FIG. 6 is a diagram showing a relationship among the concentrations ofMg, MeTFS, TBABF₄, AlCl₃, and BF₃DEE used in the synthesis of theelectrolytic solution, the heating temperature, and the dischargecapacity of the magnesium battery using the synthesized electrolyticsolution in Example 5-1 to Example 5-9 of the present invention.

(A) of FIG. 6 is a numeral table showing the concentrations, heatingtemperatures and discharge capacity described above, and (B) of FIG. 6is a diagram in which the discharge capacity shown in (A) of FIG. 6 isexpressed in the form of a graph. In (A) and (B) of FIG. 6, an axis ofordinate represents the discharge capacity (mAh/g) of thepositive-electrode active material, and an axis of abscissa representsthe Mg concentration (mol/l).

(B) of FIG. 6 is a graph showing a relationship between theconcentrations of Mg used in the synthesis of the electrolytic solutionin Example 5, and the discharge capacity of the magnesium battery. It isunderstood from FIG. 6 that the discharge capacity increasesapproximately in proportion to the concentration of Mg in a region inwhich the concentration of Mg is in the range of 0 mol/l˜0.25 mol/l, andthereafter, the discharge capacity is held approximately at a givenvalue of about 320 (mAh/g) in a region in which the concentration of Mgis in the range of 0.25 mol/l˜1.00 mol/1.

As the cause for this, it is thought that when the concentration of Mgis in the range of 0 mol/l˜0.25 mol/l, the discharge capacity of themagnesium battery is limited by the Mg concentration of the electrolyticsolution, and thus the Mg concentration of the electrolytic solution isinsufficient. On the other hand, it is thought that when theconcentration of Mg is in the range of 0.25 mol/l˜1.00 mol/l, since theMg concentration of the electrolytic solution is sufficiently much, thedischarge capacity of the magnesium battery does not depend on the Mgconcentration, and thus the discharge capacity is mainly determined bythe discharge capacity of the positive-electrode active material.

Therefore, in the magnesium battery 10 of Example 5, it can be thoughtthat the Mg concentration with which the discharge capacity reaches 320(mAh/g) is in the range of 0.25 mol/l˜1.00 mol/l, the electrolyticsolution exercises its function without a problem.

Example 6

In Example 6, the heating temperature when the electrolytic solution wassynthesized was changed in the range of 20° C.˜90° C., and the magnesiumbattery 10 was manufactured similarly to the case of Example 1 exceptfor this respect. Thus, the discharge test was carried out about themagnesium battery 10.

FIG. 7 is a diagram showing a relationship among the concentrations ofMg, MeTFS, TBABF₄, AlCl₃, and BF₃DEE used in the synthesis of theelectrolytic solution, the heating temperature, and the dischargecapacity of the magnesium battery using the synthesized electrolyticsolution in Example 6-1 to Example 6-7, and Example 1 of the presentinvention.

(A) of FIG. 7 is a numeral table showing the concentrations, heatingtemperatures and discharge capacity described above, and (B) of FIG. 7is a diagram in which the discharge capacity shown in (A) of FIG. 7 isexpressed in the form of a graph. In (A) and (B) of FIG. 7, an axis ofordinate represents the discharge capacity (mAh/g) of thepositive-electrode active material, and an axis of abscissa representsthe heating temperature (° C.).

(B) of FIG. 7 is a graph showing a relationship between the heatingtemperature when the electrolytic solution was synthesized in Example 6,and the discharge capacity of the magnesium battery of the batterymanufactured by using that electrolytic solution. As shown in FIG. 7, itis understood that the electrolytic solution synthesized in Example 6shows the favorable discharge capacity when the heating temperature isin the range of 50° C.˜80° C.

Example 7

In Example 7, the concentration of the trifluoroborane-dimethylethercomplex salt was changed in the range of 0 mol/l˜2.50 mol/l, and thusthe electrolytic solution was prepared. The magnesium battery 10 wasmanufactured similarly to the case of Example 1 except for this respect,and the discharge test was carried out about the magnesium battery 10.

FIG. 8 is a diagram showing a relationship among the concentrations ofMg, MeTFS, TBABF₄, AlCl₃, and BF₃DEE used in the synthesis of theelectrolytic solution, the heating temperature, and the dischargecapacity of the magnesium battery using the synthesized electrolyticsolution in Example 7-1 to Example 7-7, and Example 1 of the presentinvention.

(A) of FIG. 8 is a numerical table showing the concentrations, heatingtemperature and discharge capacity described above, and (B) of FIG. 8 isa diagram in which the discharge capacity shown in (A) of FIG. 8 isexpressed in the form of a graph. In (A) and (B) of FIG. 8, an axis ofordinate represents the discharge capacity (mAh/g) of thepositive-electrode active material, and an axis of abscissa representsthe BF₃DEE concentration (mol/l).

(B) of FIG. 8 is a graph showing a relationship between theconcentration of the trifluoroborane-dimethylether complex salt used inthe synthesis of the electrolytic solution in Example 7, and thedischarge capacity of the magnesium battery. As can be seen from FIG. 8,when the concentration of the trifluoroborane-dimethylether complex saltis equal to or less than 2.00 mol/l (the additive amount oftrifluoroborane-dimethylether complex salt is equal to or less than 4.00mol per 1.00 mol of Mg), the electrolytic solution synthesized inExample 7 is favorable in terms of the electrolytic solution of themagnesium battery 10.

Example 8

In example 8, the electrolytic solution was prepared by using the ethyltrifluoromethanesulfonate as the alkyl trifluoromethanesulfonate insteadof using the methyl trifluoromethanesulfonate. The magnesium battery 10was manufactured similarly to the case of Example 1 except for thisrespect, and the discharge test was carried out about the magnesiumbattery 10.

FIG. 9 is a diagram showing the discharge capacity of the magnesiumbattery using the electrolytic solution, in Example 8 of the presentinvention, which was synthesized by changing the kind of alkyltrifluoromethanesulfonate in Example 1. It is noted that in FIG. 9, RTFSmeans the kind of alkyl trifluoromethanesulfonate.

As shown in FIG. 9, even when the nonaqueous electrolytic solutioncontaining therein the magnesium ions based on the present invention ismanufactured by using any of the kinds of alkyltrifluoromethanesulfonates, with regard to the discharge capacity, thenonaqueous electrolytic solution containing therein the magnesium ionsbased on the present invention shows approximately the same performance.

Example 9

In Example 9, trifluoromethanesulfonic acid tetrabutylammonium,trifluoromethanesulfonic acid tributylmethylammonium,trifluoromethanesulfonic acid triethylmethylammonium, tetrafluoroboricacid tributylmethylammonium, tetrafluoroboric acidtriethylmethylammonium,tetrabutylammoniumbis(trifluoromethanesulfonyl)imide,tributylmethylammoniumbis(trifluoromethanesulfonyl)imide, ortriethylmethylammoniumbis(trifluoromethanesulfonyl)imide was used as thequaternary ammonium salt instead of using tetrafluoroboric acidtetrabutylammonium.

The electrolytic solution was prepared similarly to the case of Example1 except for the kinds of quaternary ammonium salts, and the magnesiumbattery 10 was manufactured. Thus, the discharge test was carried outabout the magnesium battery 10.

FIG. 10 is a diagram showing the discharge capacities of the magnesiumbatteries using the electrolytic solutions synthesized by changing thekind of quaternary ammonium salt of Example 1 in Example 9-1 to Example9-8 of the present invention.

As shown in FIG. 10, even when the nonaqueous electrolytic solutioncontaining therein the magnesium ions based on the present invention wasmanufactured by using any of the quaternary ammonium salts describedabove, with regard to the discharge capacity, the nonaqueouselectrolytic solutions each containing therein the magnesium ions basedon the present invention show approximately the same performance.

Example 10

In Example 10, a trifluoroborane-dimethyl ether complex salt, atrifluoroborane-ethyl methyl ether complex salt, atrifluoroborane-n-dibutyl ether complex salt, and atrifluoroborane-tetrahydrofuran complex salt were used as thetrifluoroborane-ether complex salt instead of using thetrifluoroborane-diethylether complex salt.

The electrolytic solution was prepared similarly to the case of Example1 except for the kind of trifluoroborane-ether complex salt, and themagnesium battery 10 was manufactured by using that electrolyticsolution thus prepared. Thus, the discharge test was carried out aboutthe magnesium battery 10.

FIG. 11 is a diagram showing the discharge capacities of the magnesiumbatteries using the electrolytic solutions synthesized by changing thekind of trifluoroborane-ether complex salt of Example 1 in Example 10-1to Example 10-4 of the present invention.

As shown in FIG. 11, even when the nonaqueous electrolytic solutioncontaining therein the magnesium ions based on the present invention wasmanufactured by using any of the trifluoroborane-ether complex saltsdescribed above, with regard to the discharge capacity, the nonaqueouselectrolytic solutions each containing therein the magnesium ions basedon the present invention show approximately the same performance.

As shown in Comparative Example 7, the THF solution of the magnesiumdichlorobutylethylaluminate described as the electrolytic solution forthe magnesium battery in the Non-Patent Document 1 needs to be treatedin the inactive gas ambient atmosphere within the argon gloved box. Onthe other hand, the nonaqueous electrolytic solution containing thereinthe magnesium ions based on the present invention can be treated withinthe dry room as the general equipment.

In addition, it is better that as shown in Example 2 to Example 7, metalmagnesium is added at the ratio of 0.25 mol/l to 1.00 mol/l to1,2-dimethoxyethane as the solvent, methyl trifluoromethanesulfonate, analuminum chloride, and tetrafluoroboric acid tetrabutylammonium areadded at the ratio of 0.80 mol˜1.20 mol, at the ratio of 1.00 mol orless, and at the ratio of 1.00 mol 2.00 mol per 1.00 mol of magnesium,and they are made to react with one another at 50° C.˜80° C. while theyare stirred, and thereafter, more preferably, 4.00 mol or less of thetrifluoroborane-diethylether complex salt per 1 mol of magnesium isadded thereto.

The nonaqueous electrolytic solution containing therein the magnesiumions of Example 10, and the method of manufacturing the same are simplerthan the conventional method because the solvent itself of theelectrolytic solution is used in the synthesis. In addition, since metalmagnesium and the magnesium salts, and other stable materials are usedas the starting materials, the management of the row materials is easy,and thus the nonaqueous electrolytic solution containing therein themagnesium ions can be manufactured at high productivity and in the highyield with the simple equipment such as the dry room. That is to say,the nonaqueous electrolytic solution containing therein the magnesiumions has a possibility that the manufacturing cost when the electrolyticsolution is put into practical use as the product is greatly reduced.

Next, a description will be given with respect to complexes which arethought to be contained in the electrolytic solutions synthesized inExamples described above. Some structures of the complexes which arethought to be generated in the nonaqueous electrolytic solutioncontaining therein the magnesium ions are considered, and examplesthereof will be described hereinafter.

FIG. 12 is a view showing examples of structures of complexes which arethought to be contained in the synthesized electrolytic solution inExample 1 of the present invention.

(A) of FIG. 12 shows an example of a structure of a complex[MgMeTFS(DME)] which is thought to be generated in the electrolyticsolution when in the synthesis of the electrolyte, a methyltrifluoromethanesulfonate (MeTFS) is used as an alkyltrifluoromethanesulfonate, tetrafluoroboric acid tetrabutylammonium(TBABF₄) is used as the quaternary ammonium salt,1,2-dimethoxyethane(DME) is used as the ether system organic solvent,and a trifluoroborane-diethylether complex salt (BF₃DEE) is used as thetrifluoroborane-ether complex salt.

(B) of FIG. 12 shows an atomic arrangement of a tetrabutylammonium ion([N(CH₂CH₂CH₂CH₃)₄]⁺) abbreviated to [TBA]⁺ in the form of a moleculemodel and a chemical formula, (C) of FIG. 12 shows an atomic arrangementof a tetrafluoroboric acid ion abbreviated to [BF₄]⁻ in the form of amolecule model and a chemical formula, (D) of FIG. 12 shows an atomicarrangement of 1,2-dimethoxyethane (CH₃OCH₂CH₂OCH₃) abbreviated to DMEin the form of a molecule model and a chemical formula, (E) of FIG. 12shows an atomic arrangement of a methyl trifluoromethanesulfonate(CF₃SO₃CH₃) abbreviated to MeTFS in the form of a molecule model and achemical formula, (F) of FIG. 12 shows an atomic arrangement of atrifluoromethane-sulfonate ion ([CF₃SO₃]⁻) in the form of a moleculemodel and a chemical formula.

From a nuclear magnetic resonance absorption spectrum and a near edgeX-ray absorption fine structure spectrum, like the example shown in (A)of FIG. 12, the complex [MgMeTFS(DME)] is through to have a structurethat a carbon atom of a methyl ion (Me⁺), an oxygen ion of atrifluoromethanesulfonate ion ([TFS]⁻), and an oxygen ion of1,2-dimethoxyethane (DME) are coordinate-bonded to a Mg atom.

DME forms together with the Mg ion the coordinate bond, therebydissolving therein the Mg ion, and the Mg ion forms the complex[MgMeTFS(DME)] as shown in (A) of FIG. 12. Also, the complex[MgMeTFS(DME)] is in a state of dissociation equilibrium, and the Mg ionis in a state of being dissolved in DME as the ether system organicsolvent.

Example 11

In Example 11, the coin type magnesium battery 10 shown in FIG. 1 wasmanufactured by using metal magnesium as the negative-electrode activematerial 5, by using the magnesium oxide as the positive-electrodeactive material, and by using the electrolytic solution based on thepresent invention. Thus, the performance of the electrolytic solutionwas examined.

<Synthesis of Nonaqueous Electrolytic Solution Containing MagnesiumIons>

0.12 g of metal magnesium was added to 10 ml of 1,2-dimethoxyethane(DME). In addition, 0.55 ml of methyl trifluoromethanesulfonate (MeTFS),2.93 g of 1-ethyl-3-methylimidazoliumbis(trifluoromethanesulfonyl)imide(EMITFSI), and 0.33 g of an aluminum chloride were added thereto. Thiscorresponds to that metal magnesium, methyl trifluoromethanesulfonate,1-ethyl-3-methylimidazoliumbis(trifluoromethanesulfonyl)imide, and analuminum chloride were added at the ratio of 0.50 mol/l, at the ratio of0.50 mol/l, at the ratio of 0.75 mol/l, and at the ratio of 0.25 mol/lto 1,2-dimethoxyethane. The heating treatment was carried out at 60° C.for 20 hours while they were stirred, thereby dissolving both themagnesium ions and the aluminum ions in 1,2-dimethoxyethane.

After that, 1.26 ml of a trifluoroborane-diethylether complex salt(BF₃DEE) was added and was then sufficiently stirred. This correspondsto that a trifluoroborane-diethylether complex salt was added at theratio of 1.00 mol/l.

<Formation of Positive-Electrode Pellet 2 and Negative-Electrode ActiveMaterial 5>

Firstly, 2 g of potassium permanganate was added to 50 ml of ahydrochloric acid having a concentration of 4 mol/l, was stirred at roomtemperature for 15 minutes, and was stationarily left. After a resultingprecipitate was filtered out and was sufficiently rinsed in water, theheating treatment was carried out at 300° C. for two hours, therebysynthesizing a manganese oxide.

Next, the manganese oxide described above, graphite as the coordinateagent, and a poly(vinylidene fluoride) (PVdF) as the binder were mixedat a mass ratio of 78:20:2 with each other. N-methylpyrrolidone (NMP)was added as the solvent to the mixture, a poly(vinylidene fluoride) asthe binder was dissolved in the mixture, and a manganese oxide andgraphite were both dissolved in the resulting liquid solution, therebyobtaining a positive-electrode mixture slurry. A heating treatment wascarried out for the resulting slurry at 120° C. for two hours, and thusNMP was vaporized from the slurry to solidify the slurry. The resultingsolidified material was pounded into powder in a mortar, therebyobtaining the positive-electrode mixture.

0.1 g of the positive-electrode mixture was weighed, and was thermallycompressed to the metallic net supporting body 3 made of nickel at apredetermined pressure to be pressure-molded into a disc-like shape,thereby forming the positive-electrode pellet 2 which was 15.5 mm indiameter and 250 μm in thickness.

On the other hand, a magnesium plate was processed to be pressure-moldedinto a disc-like shape which was 15.5 mm in diameter and was 800 μm inthickness, thereby forming the negative-electrode active material 5.

<Manufacture of Magnesium Battery 10>

The magnesium battery 10 was assembled in the dry room. Firstly, afterthe positive-electrode pellet 2 was disposed inside thepositive-electrode can 1, and the separator 6 made from a fine porousfilm made of polyethylene, and having a thickness of 25 μm was disposedon the positive-electrode pellet 2, the separator 6 was impregnated witha given amount of electrolytic liquid 7 to infuse the electrolyticliquid 7 into the separator 6. Next, the magnesium plate as thenegative-electrode active material 5 was piled on the separator 6, andthe sealing gasket 8 and the negative-electrode cup 4 were disposed inpredetermined positions, respectively. Finally, the positive-electrodecan 1 and the negative-electrode cup 4 were fitted into each otherthrough the sealing gasket 8, thereby manufacturing the coin typemagnesium battery 10 which was 20 mm in outer diameter, and was 1.6 mmin height.

<Discharge Test>

A discharge test was carried out about the magnesium battery 10 ofExample 11 manufactured in the manner as described above with a constantcurrent of 0.5 mA until the battery voltage became 0.2 V

FIG. 13 is a diagram showing a relationship among a concentrations ofMg, MeTFS, EMITFSI, AlCl₃, and BF₃DEE used in the synthesis of theelectrolytic solution, the heating temperature, and the dischargecapacity of the magnesium battery using the synthesized electrolyticsolution in Example 11 of the present invention, and Comparative Example8 to Comparative Example 13, Comparative Example 14-1, and ComparativeExample 14-2 which will be described later.

In FIG. 13, and FIG. 14 to FIG. 19 which will be described later, theMeTFS concentration means the concentration of a methyltrifluoromethanesulfonate, the EMITFSI concentration means theconcentration of1-ethyl-3-methylimidazoliumbis(trifluoromethanesulfonyl)imide, and theBF₃DEE concentration means the concentration oftrifluoroborane-diethylether complex salt.

It is noted that since an excessive amount of metal magnesium is used asthe negative-electrode active material 5, the discharge capacityobtained herein can be regarded as being determined by the dischargecapacity of the positive-electrode active material, and the performanceof the electrolytic solution.

Comparative Examples 8 to 13

In Comparative Examples 8 to 13, the influence of presence or absence of1-ethyl-3-methylimidazoliumbis(trifluoromethanesulfonyl)imide, analuminum chloride, and the trifluoroborane-diethylether complex saltwhich were used during the manufacture of the electrolytic solution 7was checked. The magnesium battery having the same structure as that ofthe magnesium battery 10 shown in FIG. 1 was manufactured similarly tothe case of Example 11 except for presence or absence thereof, and thedischarge test was carried out about the magnesium battery.

As a result, in each of Comparative Example 9, Comparative Example 10,and Comparative Example 13 each using the electrolytic solution notusing 1-ethyl-3-methylimidazoliumbis(trifluoromethanesulfonyl)imide, thedischarge capacity was not obtained at all, or only the very smalldischarge capacity was obtained. In addition, in each of ComparativeExample 8, Comparative Example 11, and Comparative Example 12 each usingthe electrolytic solution using1-ethyl-3-methylimidazoliumbis(trifluoromethanesulfonyl)imide, the largedischarge capacity was obtained, but a value of the discharge capacitythus obtained was smaller than that in Example 11.

Comparative Example 14

In Comparative Example 14, a THF solution (having a concentration of0.25 mol/l) of magnesium dichlorobutylethylaluminate(Mg[AlCl₂(C₂H₅)(C₄H₉)₂] described as the electrolytic solution for themagnesium battery in the Non-Patent Document 1 was used as theelectrolytic solution instead of using the electrolytic solution basedon the present invention. A magnesium battery having the same structureas that of the magnesium battery 10 was manufactured similarly to thecase of Example 11 except for this THF solution. In this case, inComparative Example 14-1, the magnesium battery was assembled within thedry room similarly to the case of Example 11. On the other hand, inComparative Example 14-2, the magnesium battery was assembled in aninactive gas ambient atmosphere within an argon gloved box.

Although the discharge test was carried out about each of thesemagnesium batteries similarly to the case of Example 11, the dischargecapacity was not obtained at all in Comparative Example 14-1. Thedischarge capacity obtained in the battery of Comparative Example 14-2is shown in FIG. 13.

In each of the batteries of Comparative Example 9, Comparative Example10, and Comparative Example 13, the discharge capacity was not obtained,or was very small. From this, it is understood that1-ethyl-3-methylimidazoliumbis(trifluoromethanesulfonyl)imide as a1,3-alkylmethylimidazolium salt is an essential component in theelectrolytic solution based on the present invention. In addition, theeffective discharge capacity was not obtained in the battery ofComparative Example 14-1. From this, the equipment with which themagnesium battery can be assembled in the inactive gas ambientatmosphere such as the argon gloved box is necessary for using magnesiumdichlorobutylethylaluminate described in the Non-Patent Document 1.

On the other hand, the batteries of Example 11, Comparative Example 8,Comparative Example 11, Comparative Example 12, and Comparative Example14-2 showed approximately equivalent discharge capacities. From a resultin Example 15 which will be described later, it is thought that thesedischarge capacities were mainly determined by the discharge capacity ofthe positive-electrode active material, and the electrolytic solutionexercised its function without a problem. Therefore, in batteries ofExamples which will be described below, when the discharge capacityapproximately compatible to that of the battery of Example 11, or thatof each of the batteries of Comparative Example 8, Comparative Example11, Comparative Example 12, and Comparative Example 14-2 was obtained,the electrolytic solution of the battery concerned was judged to befavorable.

Next, a synthesis condition under which the electrolytic solution basedon the present invention was favorable in terms of the electrolyticsolution of the magnesium battery was examined in Example 12 to Example16.

Example 12

In Example 12, the electrolytic solution was prepared by changing theconcentration of the methyl trifluoromethanesulfonate in the range of 0mol/l˜0.80 mol/l. The magnesium battery 10 was manufactured similarly tothe case of Example 11 except for this respect, and the discharge testwas carried out about the magnesium battery 10.

FIG. 14 is a diagram showing a relationship among the concentrations ofMg, MeTFS, EMITFSI, AlCl₃, and BF₃DEE used in the synthesis of theelectrolytic solution, the heating temperature, and the dischargecapacity of the magnesium battery using the synthesized electrolyticsolution in Comparative Example 9-1, Example 12-1 to Example 12-7, andExample 11 of the present invention.

(A) of FIG. 14 is a numerical table showing the concentrations, heatingtemperature and discharge capacity described above, and (B) of FIG. 14is a diagram in which the discharge capacity shown in (A) of FIG. 14 isexpressed in the form of a graph. In (A) and (B) of FIG. 14, an axis ofordinate represents the discharge capacity (mAh/g) of thepositive-electrode active material, and an axis of abscissa representsthe MeTFS concentration (mol/l).

(B) of FIG. 14 is a graph showing a relationship between theconcentration of the methyl trifluoromethanesulfonate used in thesynthesis of the electrolytic solution in Example 12, and the dischargecapacity of the magnesium battery. As can be seen from FIG. 14, when theconcentration of the methyl trifluoromethanesulfonate is in the range of0.40 mol/l˜0.60 mol/l (an additive amount of methyltrifluoromethanesulfonate is in the range of 0.80 mol 1.20 mol per 1.00mol of Mg), the electrolytic solution synthesized in Example 12 isfavorable in terms of the electrolytic solution of the magnesium battery10.

Example 13

In Example 13, the electrolytic solution was adjusted by changing theconcentration of 1-ethyl-3-methylimidazoliumbis(trifluorosulfonyl)imidein the range of 0 mol/l˜1.20 mol/l, and the magnesium battery 10 wasmanufactured similarly to the case of Example 11 except for thisrespect. Thus, the discharge test was carried out about the magnesiumbattery 10.

FIG. 15 is a diagram showing a relationship among the concentrations ofMg, MeTFS, EMITFSI, AlCl₃, and BF₃DEE, the heating temperature, and thedischarge capacity of the magnesium battery using the synthesizedelectrolytic solution in Comparative Example 10-1, Example 13-1 toExample 13-6, and Example 11 of the present invention.

(A) of FIG. 15 is a numerical table showing the concentrations, heatingtemperature and discharge capacity described above, and (B) of FIG. 15is a diagram in which the discharge capacity shown in (A) of FIG. 15 isexpressed in the form of a graph. In (A) and (B) of FIG. 15, an axis ofordinate represents the discharge capacity (mAh/g) of thepositive-electrode active material, and an axis of abscissa representsthe EMITFSI concentration (mol/l).

(B) of FIG. 15 is a graph showing a relationship of the concentration of1-ethyl-3-methylimidazoliumbis(trifluoromethanesulfonyl)imide, and thedischarge capacity of the magnesium battery. As can be seen from FIG.15, when the concentration of1-ethyl-3-methylimidazoliumbis(trifluorosulfonyl)imide is in the rangeof 0.50 mol/l˜1.00 mol/l (an additive amount of1-ethyl-3-methylimidazoliumbis(trifluoromethanesulfonyl)imide is in therange of 1.00 mol˜2.00 mol per 1.00 mol of Mg), the electrolyticsolution synthesized in Example 13 is favorable in terms of theelectrolytic solution of the magnesium battery 10.

Example 14

In Example 14, the electrolytic solution was adjusted by changing theconcentration of an aluminum chloride in the range of 0 mol/l˜1.00mol/l, and the magnesium battery 10 was manufactured similarly to thecase of Example 11 except for this respect. Thus, the discharge test wascarried out about the magnesium battery 10.

FIG. 16 is a diagram showing a relationship among the concentrations ofMg, MeTFS, EMITFSI, AlCl₃, and BF₃DEE, the heating temperature, and thedischarge capacity of the magnesium battery using the synthesizedelectrolytic solution in Example 14-1 to Example 14-7, and Example 11 ofthe present invention.

(A) of FIG. 16 is a numerical table showing the concentrations, heatingtemperature and discharge capacity described above, and (B) of FIG. 16is a diagram in which the discharge capacity shown in (A) of FIG. 16 isexpressed in the form of a graph. In (A) and (B) of FIG. 16, an axis ofordinate represents the discharge capacity (mAh/g) of thepositive-electrode active material, and an axis of abscissa representsthe AlCl₃ concentration (mol/l).

(B) of FIG. 16 is a graph showing a relationship of the concentration ofan aluminum chloride used in the synthesis of the electrolytic solutionin Example 14, and the discharge capacity of the magnesium battery. Ascan be seen from FIG. 16, when the concentration of the aluminumchloride is in the range of equal to or less than 0.50 mol/l (anadditive amount of aluminum chloride is equal to or less than 1.00 molper 1.00 mol of Mg), the electrolytic solution synthesized in Example 14is favorable in terms of the electrolytic solution of the magnesiumbattery 10.

Example 15

In Example 15, the electrolytic solution was adjusted by changing theconcentration of Mg in the range of 0.10 mol/l˜1.50 mol/l. In this case,the electrolytic solution was prepared in such a way that each of theconcentrations of the methyl trifluoromethanesulfonate and the aluminumchloride was equal to that of Mg, and each of the concentrations oftetrafluoroboric acid tetrabutylammonium and thetrifluoroborane-diethylether complex salt became twice that ofmagnesium. The magnesium battery 10 was manufactured similarly to thecase of Example 11 except for this respect, and the discharge test wascarried out about the magnesium battery 10.

FIG. 17 is a diagram showing a relationship among the concentrations ofMg, MeTFS, EMITFSI, AlCl₃, and BF₃DEE used in the synthesis of theelectrolytic solution, the heating temperature, and the dischargecapacity of the magnesium battery using the synthesized electrolyticsolution in Example 15-1 to Example 15-9 of the present invention.

(A) of FIG. 17 is a numeral table showing the concentrations, heatingtemperatures and discharge capacity described above, and (B) of FIG. 17is a diagram in which the discharge capacity shown in (A) of FIG. 17 isexpressed in the form of a graph. In (A) and (B) of FIG. 17, an axis ofordinate represents the discharge capacity (mAh/g) of thepositive-electrode active material, and an axis of abscissa representsthe Mg concentration (mol/l).

(B) of FIG. 17 is a graph showing a relationship between theconcentration of Mg used in the synthesis of the electrolytic solutionin Example 15, and the discharge capacity of the magnesium battery. Itis understood from FIG. 17 that the discharge capacity increasesapproximately in proportion to the concentration of Mg in a region inwhich the concentration of Mg is in the range of 0 mol/l˜0.25 mol/l, andthereafter, the discharge capacity is held approximately at a givenvalue of about 320 (mAh/g) in a region in which the concentration of Mgis in the range of 0.25 mol/l˜1.00 mol/l.

As the cause for this, it is thought that when the concentration of Mgis in the range of 0 mol/l˜0.25 mol/l, the discharge capacity of themagnesium battery is limited by the Mg concentration of the electrolyticsolution, and thus the Mg concentration of the electrolytic solution isinsufficient. On the other hand, it is thought that when theconcentration of Mg is in the range of 0.25 mol/l˜1.00 mol/l, since theMg concentration of the electrolytic solution is sufficiently much, thedischarge capacity of the magnesium battery does not depend on the Mgconcentration, and thus the discharge capacity is mainly determined bythe discharge capacity of the positive-electrode active material.

Therefore, in the magnesium battery 10 of Example 15, it can be thoughtthat the Mg concentration with which the discharge capacity reaches 320(mAh/g) is in the range of 0.25 mol/l˜1.00 mol/l, the electrolyticsolution exercises its function without a problem.

Example 16

In Example 16, the heating temperature when the electrolytic solutionwas synthesized was changed in the range of 20° C.˜90° C., and themagnesium battery 10 was manufactured similarly to the case of Example11 except for this respect. Thus, the discharge test was carried outabout the magnesium battery 10.

FIG. 18 is a diagram showing a relationship among the concentrations ofMg, MeTFS, EMITFSI, AlCl₃, and BF₃DEE used in the synthesis of theelectrolytic solution, the heating temperature, and the dischargecapacity of the magnesium battery using the synthesized electrolyticsolution in Example 16-1 to Example 16-7, and Example 11 of the presentinvention.

(A) of FIG. 18 is a numeral table showing the concentrations, heatingtemperatures and discharge capacity described above, and (B) of FIG. 18is a diagram in which the discharge capacity shown in (A) of FIG. 18 isexpressed in the form of a graph. In (A) and (B) of FIG. 18, an axis ofordinate represents the discharge capacity (mAh/g) of thepositive-electrode active material, and an axis of abscissa representsthe heating temperature (° C.).

(B) of FIG. 18 is a graph showing a relationship of the heatingtemperature when the electrolytic solution is synthesized in Example 16,and the discharge capacity of the magnesium battery of the batterymanufactured by using that electrolytic solution. As shown in FIG. 18,it is understood that the electrolytic solution synthesized in Example16 shows the favorable discharge capacity when the heating temperatureis in the range of 50° C.˜80° C.

Example 17

In Example 17, the electrolytic solution was prepared by changing theconcentration of a trifluoroborane-diethylether complex salt in therange of 0 mol/l˜2.50 mol/l, and the magnesium battery 10 wasmanufactured similarly to the case of Example 11 except for thisrespect. Thus, the discharge test was carried out about the magnesiumbattery 10.

FIG. 19 is a diagram showing a relationship among the concentrations ofMg, MeTFS, EMITFSI, AlCl₃, and BF₃DEE used in the synthesis of theelectrolytic solution, the heating temperature, and the dischargecapacity of the magnesium battery using the synthesized electrolyticsolution in Example 17-1 to Example 17-7, and Example 11 of the presentinvention.

(A) of FIG. 19 is a numeral table showing the concentrations, heatingtemperatures and discharge capacity described above, and (B) of FIG. 19is a diagram in which the discharge capacity shown in (A) of FIG. 19 isexpressed in the form of a graph. In (A) and (B) of FIG. 19, an axis ofordinate represents the discharge capacity (mAh/g) of thepositive-electrode active material, and an axis of abscissa representsthe BF₃DEE concentration (mol/l).

(B) of FIG. 19 is a graph showing a relationship between theconcentration of the trifluoroborane-diethylether complex salt used inthe synthesis of the electrolytic solution in Example 17, and thedischarge capacity of the magnesium battery. As can be seen from FIG.19, when the concentration of the trifluoroborane-diethylether complexsalt is equal to or less than 2.00 mol/l (the additive amount oftrifluoroborane-diethylether complex salt is equal to or less than 4.00mol per 1.00 mol of Mg), the electrolytic solution synthesized inExample 17 is favorable in the terms of the electrolytic solution of themagnesium battery 10.

Example 18

In example 18, the electrolytic solution was prepared by using the ethyltrifluoromethanesulfonate as the alkyl trifluoromethanesulfonate insteadof using the methyl trifluoromethanesulfonyl. The magnesium battery 10was manufactured similarly to the case of Example 11 except for thisrespect, and the discharge test was carried out about the magnesiumbattery 10.

FIG. 20 is a diagram showing the discharge capacity of the magnesiumbattery using the electrolytic solution, in Example 18 of the presentinvention, which was synthesized by changing the kind of alkyltrifluoromethanesulfonate in Example 11. It is noted that in FIG. 20,RTFS means the kind of alkyl trifluoromethanesulfonate.

As shown in FIG. 20, even when the nonaqueous electrolytic solutioncontaining therein the magnesium ions based on the present invention ismanufactured by using any of the kinds of alkyltrifluoromethanesulfonates, with regard to the discharge capacity, thenonaqueous electrolytic solutions each containing therein the magnesiumions based on the present invention show approximately the sameperformance.

Example 19

In example 19, 1,3-dimethylimidazoliumtetrafluoroborate,1-ethyl-3-methylimidazoliumtetrafluoroborate,1-butyl-3-methylimizadoliumtetrafluoroborate,1,3-dimethylimidazoliumbis(trifluoromethanesulfonyl)imide, or1-butyl-3-methylimidazoliumbis(trifluoromethanesulfonyl)imide was usedas a 1,3-alkylmethylimidazolium salt instead of using1-ethyl-3-methylimidazoliumbis(trifluoromethanesulfonyl)imide.

The electrolytic solution was prepared similarly to the case of Example11 except for the kind of 1,3-alkylmethylimidazolium salt, and themagnesium battery 10 was manufactured using the electrolytic solutionthus prepared. Thus, the discharge test was carried out about themagnesium battery 10.

FIG. 21 is a diagram showing the discharge capacities of the magnesiumbatteries using the electrolytic solutions synthesized by changing thekind of 1,3-alkylmethylimidazolium salt of Example 11 in Example 19-1 toExample 19-5 of the present invention.

As shown in FIG. 21, even when the nonaqueous electrolytic solutioncontaining therein the magnesium ions based on the present invention wasmanufactured by using any of the 1,3-alkylmethylimidazolium saltsdescribed above, with regard to the discharge capacity, the nonaqueouselectrolytic solutions each containing therein the magnesium ions basedon the present invention show approximately the same performance.

Example 20

In Example 20, a trifluoroborane-dimethyl ether complex salt, atrifluoroborane-ethyl methyl ether complex salt, atrifluoroborane-n-dibutyl ether complex salt, or atrifluoroborane-tetrahydrofuran complex salt was used as thetrifluoroborane-ether complex instead of using thetrifluoroborane-diethylether complex salt.

The electrolytic solution was prepared similarly to the case of Example11 except for the kind of 1,3-alkylmethylimidazolium salt, and themagnesium battery 10 was manufactured by using the electrolytic solutionthus prepared. Thus, the discharge test was carried out about themagnesium battery 10.

FIG. 22 is a diagram showing the discharge capacities of the magnesiumbatteries using the electrolytic solutions synthesized by changing thekind of trifluoroborane-ether complex salt of Example 11 in Example 20-1to Example 20-4 of the present invention.

As shown in FIG. 22, even when the nonaqueous electrolytic solutioncontaining therein the magnesium ions based on the present invention wasmanufactured by using any of the trifluoroborane-ether complex saltsdescribed above, with regard to the discharge capacity, the nonaqueouselectrolytic solutions each containing therein the magnesium ions basedon the present invention show approximately the same performance.

As shown in Comparative Example 14, the THF solution of the magnesiumdichlorobutylethylaluminate described as the electrolytic solution forthe magnesium battery in the Non-Patent Document 1 needs to be treatedin the inactive gas ambient atmosphere within the argon gloved box. Onthe other hand, the nonaqueous electrolytic solution containing thereinthe magnesium ions based on the present invention can be treated withinthe dry room as the general equipment.

In addition, it is better that as shown in Example 12 to Example 17,metal magnesium is added at the ratio of 0.25 mol/l˜1.00 mol/l to1,2-dimethoxyethane as the solvent, and the methyltrifluoromethanesulfonate,1-ethyl-3-methylimidazoliumbis(trifluoromethanesulfonyl)imide, and thealuminum chloride are added at the ratio of 0.80 mol˜1.20 mol, at theratio of 1.00 mol˜2.00 mol, and at the ratio of 1.00 mol or less per1.00 mol of magnesium, and they are made to react with one another at50° C.˜80° C. while they are stirred, and thereafter, more preferably,4.00 mol or less of the trifluoroborane-diethylether complex salt per 1mol of magnesium is added thereto.

The nonaqueous electrolytic solution containing therein the magnesiumions of Example 20, and the method of manufacturing the same are simplerthan the conventional method because the solvent itself of theelectrolytic solution is used in the synthesis. In addition, since metalmagnesium and the magnesium salts, and other stable materials are usedas the starting materials, the management of the row materials is easy,and thus the nonaqueous electrolytic solution containing therein themagnesium ions can be manufactured at high productivity and in the highyield with the simple equipment such as the dry room. That is to say,the nonaqueous electrolytic solution containing therein the magnesiumions has a possibility that the manufacturing cost when the electrolyticsolution is put into practical use as the product is greatly reduced.

Next, a description will be given with respect to complex salts whichare thought to be contained in the electrolytic solutions synthesized inExamples of the present invention described above. Some structures ofthe complex salts which are thought to be generated in the nonaqueouselectrolytic solution containing therein the magnesium ions areconsidered, and examples thereof will be described hereinafter.

FIG. 23 is a view showing examples of structures of complex salts whichare thought to be contained in the synthesized electrolytic solution inExample 11 of the present invention.

(A) of FIG. 23 shows an example of a structure of a complex salt[MgMeTFSI(DME)] which is thought to be generated in the electrolyticsolution when in the synthesis of the electrolyte, a methyltrifluoromethanesulfonate (MeTFS) was used as an alkyltrifluoromethanesulfonate,1-ethyl-3-methylimidazoliumbis(trifluoromethanesulfonyl)imide (EMITFSI)was used as a 1,3-alkylmethylimidazolium salt, 1,2-dimethoxyethane(DME)was used as the ether system organic solvent, and atrifluoroborane-diethylether complex salt (BF₃DEE) was used as thetrifluoroborane-ether complex salt.

(B) of FIG. 23 shows an atomic arrangement of abis(trifluoromethanesulfonyl)imide ion([(CF₃SO₂)₂N]⁻) abbreviated to[TFSI]⁻ in the form of a molecule model and a chemical formula, (C) ofFIG. 23 shows an atomic arrangement of a 1-ethyl-3-methylimidazolium ion([CH₃CH₂(C₃H₃N₂)CH₃]⁺) abbreviated to [EMI]⁺ in the form of a moleculemodel and a chemical formula, (D) of FIG. 23 shows an atomic arrangementof 1,2-dimethoxyethane (CH₃OCH₂CH₂OCH₃) abbreviated to DME in the formof a molecule model and a chemical formula, (E) of FIG. 23 shows anatomic arrangement of a methyl trifluoromethanesulfonic acid (CF₃SO₃CH₈)abbreviated to MeTFS in the form of a molecule model and a chemicalformula, and (F) of FIG. 23 shows an atomic arrangement of atrifluoromethanesulfonic acid ([CF₃SO₃]⁻) abbreviated to [TFS]⁻ in theform of a molecule model and a chemical formula.

From a nuclear magnetic resonance absorption spectrum and a near edgeX-ray absorption fine structure spectrum, like the example shown in (A)of FIG. 23, the complex [MgMeTFSI(DME)] is thought to have a structurethat a carbon atom of a methyl ion (Me⁺), an oxygen ion of abis(trifluoromethanesulfonyl)imide ion [TFSI]⁻, and an oxygen atom of1,2-dimethoxyethane (DME) are coordinate-bonded to a Mg atom.

DME forms together with the Mg ion the coordinate bond, therebydissolving therein the Mg ion, and the Mg ion forms the complex[MgMeTFSI(DME)] as shown in (A) of FIG. 23. Also, the complex[MgMeTFSI(DME)] is in a state of dissociation equilibrium, and the Mgion is in a state of being dissolved in DME as the ether system organicsolvent.

Example Magnesium Battery Using Nonaqueous Electrolytic SolutionContaining Magnesium Ions Simultaneously Using Quaternary Ammonium Saltand 1,3-Alkylmethylimidazolium Salt

In this Example, the coin type magnesium battery 10 shown in FIG. 1 wasmanufactured by using metal magnesium as the negative-electrode activematerial 5, by using the manganese oxide as the positive-electrodeactive material, and by using both the quaternary ammonium salt and the1,3-alkylmethylimidazolium salt. Thus, the discharge capacity of themagnesium battery 10 was measured.

The electrolytic solution was prepared by using tetrafluoroboric acidtetrabutylammonium as the quaternary ammonium salt, and by using1-ethyl-3-methylimidazoliumbis(trifluoromethanesulfonyl)imide as the1,3-alkylmethylimidazolium salt.

<Synthesis of Nonaqueous Electrolytic Solution 7 Containing MagnesiumIons>

0.12 g of metal magnesium was added to 10 ml of 1,2-dimethoxyethane. Inaddition, 0.55 ml of methyl trifluoromethanesulfonate (MeTFS), 1.235 gof tetrafluoroboric acid tetrabutylammonium (TBABF₄), 1.465 g of1-ethyl-3-methylimidazoliumbis(trifluoromethanesulfonyl)imide (EMITFSI), and 0.33 g of an aluminum chloride (AlCl₃) were added thereto. Thiscorresponds to that metal magnesium, methyl trifluoromethanesulfonate,tetrafluoroboric acid tetrabutylammonium,1-ethyl-3-methylimidazoliumbis(trifluoromethanesulfonyl)imide, and analuminum chloride were added at the ratio of 0.50 mol/l, at the ratio of0.50 mol/l, at the ratio of 0.35 mol/l, at the ratio of 0.35 mol/l, andat the ratio of 0.25 mol/l to 1,2-dimethoxyethane. The heating treatmentwas carried out at 60° C. for 20 hours while they were stirred, therebydissolving both the magnesium ions and the aluminum ions in1,2-dimethoxy ethane.

In the electrolytic solution of this Example, tetrafluoroboric acidtetrabutylammonium and1-ethyl-3-methylimidazoliumbis(trifluoromethanesulfonyl)imide are addedat the ratio of 1.50 mol per 1.00 mol of metal magnesium.

After that, 1.26 ml of a trifluoroborane-diethylether complex salt(BF₃DEE) was added and was then sufficiently stirred. This correspondsto that a trifluoroborane-diethylether complex salt was added at theratio of 1.00 mol/l.

The positive-electrode pellet 2 and the negative-electrode activematerial 5 were both formed, thereby manufacturing the magnesium battery10 similarly to the case of each of Example 1 and Example 11, and thedischarge test was carried out about the magnesium battery 10. As aresult, there was obtained approximately the same discharge capacity asthat in each of Example 1 and Example 11.

The magnesium battery in each of Examples which will be described belowis a nonaqueous electrolytic solution system battery which uses either amagnesium metal or a magnesium alloy as the negative-electrode materialand uses a graphite fluoride as the positive-electrode active material,and a battery which uses copper.

The magnesium battery in each of Examples which will be described belowincludes a positive-electrode pellet 2 into which a positive-electrodemixture composed of the positive-electrode active material made from thegraphite fluoride, a conductive agent such as graphite, and a bindersuch as a poly(vinylidene fluoride) is pressure-molded together with anet-like positive-electrode power collecting body so as to have adisc-like shape, a positive-electrode can 1, a negative-electrode cup 4,a negative-electrode active material 5 containing therein either amagnesium metal or a magnesium alloy, a porous separator 6 impregnatedwith an electrolytic solution 7, and a sealing gasket 8.

In addition, although in each of following Examples, a coin type batteryis described, the present invention can also be applied to a cylindertype or square type battery having a spiral structure in its inside inwhich a thin positive electrode and a thin negative electrode betweenwhich a separator is held are wound into a spiral shape as long as thepositive-electrode active material has the structure of contactingcopper, and thus the same effects as those in the coin type battery canbe obtained.

It is noted that in each of Example 21-1 to Example 21-13 which will bedescribed later, the positive-electrode mixture described above furthercontains therein copper power. In addition, in Example 22 which will bedescribed later, the positive-electrode mixture not containing thereincopper power and a metallic net supporting body 3 made of copper areboth used. Moreover, in Example 23 which will be described later, apositive-electrode mixture not containing therein copper powder, ametallic net supporting body 3 made of non-copper, and thepositive-electrode can 1 having an inner surface covered with copper areused.

With regard to the negative-electrode active material 5, a magnesiummetal, a magnesium alloy obtained by adding an alloy element such asaluminum to magnesium, or the like can be used.

For example, a fine porous film made of a polyolefin system such aspolypropylene or polyethylene, or the like can be used in the separator6.

Metal magnesium, an alkyl trifluoromethanesulfonic acid, a quaternaryammonium salt or/and a 1,3-alkylmethylimidazolium salt are added to anether system organic solvent and are then heated, thereby making itpossible to prepare the nonaqueous electrolytic solution in which themagnesium ions are dissolved in the ether system organic solvent.

The nonaqueous electrolytic solution, for example, is a liquid solutionobtained by dissolving either a suitable salt containing thereinmagnesium ions or metal magnesium (Mg) in an aprotic solvent. Forexample, a liquid solution which is synthesized (prepared) from metalmagnesium, a methyl trifluoromethanesulfonate (CH₃CF₃SO₃),1-ethyl-3-methylimidazoliumbis(trifluoromethanesulfonyl)imide([C₂H₅(C₃H₃N₂)CH₃](SO₂CF₃)₂N)as a 1-ethyl-3-methylimidazolium salt, and 1,2-dimethoxyethane(CH₃OCH₂CH₂OCH₃), or the like can be used as the nonaqueous electrolyticsolution.

Example 21

In Example 21, a description will now be given with respect to amagnesium battery using a positive-electrode mixture containing thereina positive-electrode active material made from a graphite fluoride, andcopper.

<Formation of Positive-Electrode Pellet 2>

Powder of the graphite fluoride as the positive-electrode activematerial, powder of metal copper, power of graphite as the conductiveagent, and powder of a poly(vinylidene fluoride) as the binder are mixedwith one another. The mixing was carried out at a composition such thata mass ratio of graphite to the graphite fluoride ((mass ofgraphite/mass of graphite fluoride)×100), and a mass ratio of copper tothe graphite fluoride ((mass of copper)/mass of graphite fluoride)×100)become predetermined values, respectively.

This mixture was dispersed in an N-methyl-2-pyrrolidone (NMP) solutionto obtain a positive-electrode mixture slurry. The resulting slurry wasdried at 120° C. for two hours to volatilize NMP, and the resultingsolidified material was pounded into powder in a mortar, therebyobtaining a positive-electrode mixture. 0.1 g of the positive-electrodemixture was weighed and was then pressure-molded with an expanded metalmade of nickel (Ni) as a positive-electrode power collecting body at apredetermined pressure so as to have a disc-like shape, therebyobtaining a positive-electrode pellet having a diameter of 15.5 mm and athickness of 250 μm. It is noted that in the used expanded metal made ofNi (manufactured by Thank-Metal Co., Ltd.), a distance of center in amesh short-width direction=SW=0.75 mm, a distance of center in a meshlong-width direction=LW=1.50 mm, a step size=W=0.1 mm, and a thicknessof a material=T=0.1 mm.

A magnesium plate was processed to be molded so as to obtain a disc-likeshape having a diameter of 15.5 mm and a thickness of 800 μm, therebyforming the negative electrode pellet.

<Preparation of Nonaqueous Electrolytic Solution 7 Containing MagnesiumIons>

Metal magnesium, a methyl trifluoromethane sulfonate, and1-ethyl-3-methylimidazoliumbis(trifluoromethanesulfonyl)imide were addedat a ratio of 0.25 mol/L, at a ratio of 0.25 mol, and at a ratio of 0.5mol to a 1,2-dimethoxyethane solution. A heating treatment was carriedout at 60° C. for 20 hours while they were stirred, thereby obtaining anelectrolytic solution.

Next, a fine-porous separator made of polyethylene and having athickness of 25 μm was placed on a positive-electrode can made ofstainless in which the positive-electrode pellet was accommodated, agiven amount of electrolytic solution thus manufactured was infused fromthe fine-porous separator, and the negative-electrode pellet describedabove, a sealing gasket, and a negative-electrode cup made of stainlesswere laminated in order therefrom. Finally, they were fitted into oneanother, and were recovered from an argon gloved box, therebymanufacturing a coin type battery having an external shape of 20 mm, anda height of 1.6 mm.

Comparative Example 15

In the battery of Example 21, a battery having a structure that acontent of copper in the positive-electrode mixture was 0 (zero) wasmanufactured.

FIG. 24 shows a relationship about the discharge capacity of thepositive-electrode mixture in Examples of the present invention, and isa diagram showing a relationship between a mass ratio of copper to thegraphite fluoride ((mass of copper/mass of graphite fluoride)×100), andthe discharge capacity of the graphite fluoride when copper is added tothe positive-electrode mixture.

(A) of FIG. 24 is a numeral table showing the positive electrode mixtureand discharge capacity described above, and (B) of FIG. 24 is a diagramin which (A) of FIG. 24 is expressed in the form of a graph. In (A) and(B) of FIG. 24, an axis of ordinate represents the discharge capacity(mAh/g) of the graphite fluoride, and an axis of abscissa represents themass ratio of copper to the graphite fluoride ((mass of copper/mass ofgraphite fluoride)×100).

The positive-electrode mixtures for which the powder of the graphitefluoride (CF), the powder of metal copper (Cu), the powder of graphite(C), and the power of a poly(vinylidene fluoride) (PFV) were weighed atmass compositions (%) as shown in (A) of FIG. 24, and which wasmanufactured in accordance with the method described above were used inthe magnesium batteries of Example 21-1 to Example 21-13, and ComparisonExample 15, respectively.

With regard to the magnesium batteries thus manufactured in Example 21-1to Example 21-13, and Comparison Example 15, the discharge test wascarried out with a constant current of 0.1 mA until the battery voltagebecame zero V, and the discharge capacities were evaluated.

FIG. 25 is a diagram showing a change in discharge capacity in Exampleof the present invention, and showing the discharge capacities of thepositive electrodes with respect to Comparative Example 15 and Example21-10 as an example. In FIG. 25, an axis of ordinate represents thevoltage (V), and an axis of abscissa represents the positive electrodedischarge capacity (mAh/g).

As a result of the discharge tests, there are obtained the dischargecapacities as shown in the rightmost side column in a table of (A) ofFIG. 24, and as shown in a graph of (B) of FIG. 24, respectively. Fromthe results shown in FIG. 24, as compared with the case of the magnesiumbattery of Comparative Example 15 in which copper is not added to thepositive-electrode mixture, by adding copper to the positive-electrodemixture, the discharge capacity of the graphite fluoride becomes large,and thus the effect of increasing the discharge capacity is obtainedwhen the mass ratio of copper to the graphite fluoride ((mass ofcopper/mass of graphite fluoride)×100) is equal to or larger than 3.0.In addition, the discharge capacity is approximately constant when thatmass ratio exceeds 15.0. This discharge capacity is about 7.2 times aslarge as that of the battery of Comparative Example 15, and becomes avalue corresponding to about 99% of the theoretical capacity.

As apparent from the results shown in FIG. 24, each of the dischargecapacities of the batteries of Example 21-10 to Example 21-13 becomesabout 7.1 times or more as large as that of Comparative Example 15, andthus is very large. It is obvious that in the magnesium graphitefluoride battery, it is preferable to use the positive-electrode mixturecontaining therein copper.

As shown in (B) of FIG. 24, when the ratio of copper added to thepositive-electrode mixture, that is, the ratio (mass of copper/mass ofgraphite fluoride)×100 is 8.5, 10.0, 12.3, 15.0, the discharge capacityreaches 70%, 80%, 90%, 98.8% of the theoretical capacity (about 860mAh/g).

Since copper itself in the positive-electrode mixture does not have thedischarge capacity similarly to graphite as the conductive agent or apoly(vinylidene fluoride) as the binder, it is suitable that the massratio of copper to the graphite fluoride is equal to or smaller than anupper limit value in which the effect of increasing the dischargecapacity is obtained. Therefore, in the magnesium graphite fluoridebattery, when copper is added to the positive-electrode mixture in orderto obtain the effect of increasing the discharge capacity, it ispreferable that the mass of copper is made equal to or larger than 3.0and equal to or smaller than 15.0 per the mass of 100 of the graphitefluoride.

In addition, since when the mass of copper is made at least 8.5, 10.0,12.3, 15.0 per the mass of 100 of the graphite fluoride, 70%, 80%, 90%,98.8% of the theoretical capacity can be obtained. Thus, a large amountof copper needs not to be contained in the positive-electrode mixture,and an increase in inner volume of the battery is prevented from beingcaused.

Example 22

In Example 22, a description will now be given with respect to amagnesium battery using a positive-electrode power collecting body madeof copper without using the positive-electrode mixture containingtherein the positive-electrode active material made from the graphitefluoride, and copper.

The magnesium battery of Example 22 was manufactured similarly to thecase of the battery of Comparative Example 15 except that thepositive-electrode power collecting body was made of an expanded metalmade from copper (Cu) instead of being made of the expanded metal madefrom nickel in the battery of Comparative Example 15. It is noted thatin the used expanded metal made of Cu (manufactured by Thank-Metal Co.,Ltd.), the distance of center in the mesh short-width direction=SW=0.75mm, the distance of center in the mesh long-width direction=LW=1.50 mm,the step size=W=0.1 mm, and the thickness of the material=T=0.1 mm.

With regard to the battery thus manufactured of Example 22, thedischarge test was carried out with the constant current of 0.1 mA untilthe battery voltage became zero V similarly to the case of the batteryof Example 21.

FIG. 26 is a diagram showing a discharge capacity of the graphitefluoride when the positive-electrode power collecting body made ofcopper is used in Example of the present invention.

As apparent from the results shown in FIG. 26, the discharge capacity ofthe battery of Example 22 in which the positive-electrode powercollecting body is made of the expanded metal made from Cu is about 7.0times as large as that of the battery of Comparative Example 15 in whichthe positive-electrode power collecting body is made of the expandedmetal made from Ni. The discharge capacity of the battery of Example 22is a value close to each of the discharge capacities of the batteries ofExample 21-10 to Example 21-13, and corresponds to about 96% of thetheoretical capacity. The battery of Example 22 is very large indischarge capacity, and thus it is obvious that in the magnesiumgraphite fluoride battery, it is preferable to use a positive-electrodepower collecting body made of copper.

It is noted that the positive-electrode power collecting body made of ametal (conductive material) covered with copper can also be used insteadof using the positive-electrode power collecting body made of copper.The positive-electrode power collecting body can be manufactured byusing a conductive material covered with copper through evaporation orsputtering of copper onto a surface of a metal other than copper, and byusing a cladding material in which a surface of a metal other thancopper clads in copper. For example, it is possible to use thepositive-electrode power collecting body which is covered with copperthrough the evaporation or sputtering of copper onto the surface of theexpanded metal made of Ni.

Example 23

In Example 23, a description will now be given with respect to amagnesium battery using a positive-electrode can having an inner surfacecovered with copper without using the positive-electrode mixturecontaining therein the positive-electrode active material made from thegraphite fluoride, and copper, and without using the positive-electrodepower collecting body made of copper.

The magnesium battery of Example 23 was manufactured similarly to thecase of the battery of Comparative Example 15 except that apositive-electrode can having an inner surface covered with copper wasused instead of using the positive-electrode can made of stainless inthe battery of Comparative Example 15. Also, the positive-electrode canmade of a cladding material cladding in stainless and copper was used.

With regard to the battery thus manufactured of Example 23, thedischarge test was carried out with the constant current of 0.1 mA untilthe battery voltage became zero V similarly to the case of each of thebatteries of Example 21 and Example 22.

FIG. 27 is a diagram showing the discharge capacity of the graphitefluoride when the inner surface of the positive-electrode can is coveredwith copper in Example of the present invention.

As apparent from the results shown in FIG. 27, the discharge capacity ofthe battery of Example 23 using the positive-electrode can having theinner surface covered with copper is about 6.8 times as large as that ofthe battery of Comparative Example 15 using the positive-electrode canmade of stainless. Although the discharge capacity of the battery ofExample 23 is slightly smaller than that of each of the batteries ofExample 21-10 to Example 21-13, the discharge capacity of the battery ofExample 23 corresponds to about 93% of the theoretical capacity. Thebattery of Example 23 is very large in discharge capacity, and thus itis obvious that in the magnesium graphite fluoride battery, it ispreferable to use the positive-electrode can having the inner surfacecovered with copper.

It is noted that the positive-electrode can having the inner surfacecovered with copper can be manufactured by using either the claddingmaterial in which a metal other than copper clads in copper, or thematerial covered with copper through the evaporation or sputtering ofcopper onto a surface of a metal other than copper.

Example Magnesium Battery in which Composition of Electrolytic Solutionis Changed

Although in each of Examples 21 to 23, the magnesium battery wasmanufactured by using the electrolytic solution prepared by using1-ethyl-3-methylimidazoliumbis(trifluoromethanesulfonyl)imide, in thisExample, the magnesium battery was manufactured by using an electrolyticsolution prepared by using tetrafluoroboric acid tetrabutylammonium ineach of Example 21 to Example 23.

<Preparation of Nonaqueous Electrolytic Solution 7 Containing MagnesiumIons>

Metal magnesium, a methyl trifluoromethanesulfonate, andtetrafluoroboric acid tetrabutylammonium were added at a ratio of 0.25mol/L, at a ratio of 0.25 mol, and at a ratio of 0.5 mol to a1,2-dimethoxyethane solution. A heating treatment was carried out at 60°C. for 20 hours while they were stirred, thereby obtaining anelectrolytic solution.

The discharge test was carried out about the magnesium battery 10manufactured by using this electrolytic solution. As a result, there wasobtained approximately the same discharge capacity as that of each ofthe magnesium batteries of Example 21-11, Example 22, and Example 23.

As set forth hereinabove, by adopting the structure in which thepositive-electrode active material contacts copper, it is possible toprovide the magnesium battery having the very large discharge capacity.

Although in Examples described above, the description has been givenwith respect to the battery using the positive-electrode mixturecontacting therein both the positive-electrode active material made fromthe graphite fluoride, and copper (Example 21), the battery using eitherthe positive-electrode power collecting body made of copper or thepositive-electrode power collecting body made of a metal (conductivematerial) covered with copper (Example 22), and the battery using thepositive-electrode can having the inner surface covered with copper(Example 23), the magnesium battery having the discharge capacitycorresponding to about 99% of the theoretical capacity can also bemanufactured by using a combination of any of two or more of (1) thestructure of the positive-electrode mixture containing therein copper,(2) the structure of either the positive-electrode power collecting bodymade of copper or the positive-electrode power collecting body coveredwith copper, and (3) the structure of the positive-electrode can havingthe inner surface covered with copper.

Although the present invention has been described so far with respect tothe embodiments, the present invention is by no means limited to theembodiments described above, and thus various kinds of changes can bemade based on the technical idea of the present invention.

For example, in the electrochemical device based on the presentinvention suitable for either the primary battery or the secondarybattery, the shape, structure, material and the like thereof can besuitably selected without departing from the present invention, and thusthe present invention can be suitably applied to the batteries havingvarious shapes such as a cylinder type, a square type, a coin type and awinding type, and various sizes.

INDUSTRIAL APPLICABILITY

The electrochemical device according to the present invention canprovide the magnesium secondary battery or the like having the structurewith which the superior characteristics of the negative-electrode activematerial, such as the large energy capacity, which a polyvalent metalsuch as metal magnesium has can be sufficiently brought out, and whichmakes the miniaturization, the light weight, and the portableinstrumentation of the small electronic apparatus possible, therebyrealizing the enhancement of the convenience and the price reduction.

EXPLANATION OF REFERENCE NUMERALS

-   -   1 . . . Positive-electrode can, 2 . . . Positive-electrode        pellet, 3 . . . Metal net supporting body, 4 . . .        Negative-electrode cup, 5 . . . Negative-electrode active        material, 6 . . . Separator, 7 . . . Electrolytic solution, 8 .        . . Sealing gasket, 10 . . . Magnesium battery, 11 . . .        Positive electrode, 12 . . . Negative electrode

1-20. (canceled)
 21. A nonaqueous electrolytic solution comprisingmagnesium ions dissolved in an ether system organic solvent in which atleast one of metal magnesium, alkyl trifluoromethanesulfonate having ageneral formula RCF₃SO₃, a quaternary ammonium salt having a generalformula R¹R²R³R⁴N⁺Z⁻ and a 1,3-alkyl methylimidazolium salt having ageneral formula R(C₃H₃N₂)CH₃]⁺X⁻ are added to the ether system organicsolvent; wherein in the general formula RCF₃SO₃, R is a methyl group oran ethyl group; wherein in the general formula R¹R²R³R⁴N⁺Z⁻, each of R¹,R², R³, and R⁴ is an alkyl group or an aryl group, and Z⁻ is any one ofa chloride ion (Cl⁻), a bromide ion (Br⁻), an iodine ion (I⁻), an aceticacid ion (CH₃COO⁻), a perchloric acid ion (ClO₄ ⁻), a tetrafluoroboricacid ion (BF₄ ⁻), a hexafluorophosphoric acid ion (PF₆ ⁻), ahexafluoroarsenic acid ion (AsF₆ ⁻), a perfluoroalkylsulfonic acid ion(Rf1SO₃ ⁻) where Rf1 is a perfluoroalkyl group, and aperfluoroalkylsulfonyl imide ion ((Rf2SO₂)₂N⁻) where Rf2 is aperfluoroalkyl group; and wherein in the general formula[R(C₃H₃N₂)CH₃]⁺X⁻, R is a methyl group, an ethyl group or a butyl group,and X⁻ is any one of a tetrafluoroboric acid ion (BF₄ ⁻) and abis(trifluoromethanesulfonyl)imide ion ((SO₂CF₃)₂N⁻).
 22. The nonaqueouselectrolytic solution according to claim 21, wherein an aluminum halidehaving a general formula AlY₃ is added to the ether system organicsolvent, wherein in the general formula AlY₃, Y is any one of chlorine(Cl), bromine (Br), and iodine (I).
 23. The nonaqueous electrolyticsolution according to claim 22, wherein the aluminum halide is analuminum chloride, and the aluminum halide is added at a ratio of 1.0mol or less per 1.0 mol of metal magnesium.
 24. The nonaqueouselectrolytic solution according to claim 21, wherein at least one typeof trifluoroborane-ether complex salt (BF₃(ether)) selected from thegroup consisting of a trifluoroborane-dimethyl ether complex salt, atrifluoroborane-ethyl methyl ether complex salt, atrifluoroborane-diethyl ether complex salt, a trifluoroborane-n-dibutylether complex salt, and a trifluoroborane-tetrahydrofuran complex saltis added.
 25. The nonaqueous electrolytic solution according to claim24, wherein the trifluoroborane-ether complex salt is added at a ratioof 4.0 mol or less per 1.0 mol of the metal magnesium.
 26. Thenonaqueous electrolytic solution according to claim 21, wherein thealkyl trifluoromethanesulfonate is at least one type selected from thegroup consisting of a methyl trifluoromethanesulfonate and an ethyltrifluoromethanesulfonate, and the alkyl trifluoromethanesulfonate isadded at a ratio of equal to or more than 0.8 mol and equal to or lessthan 1.2 mol per 1.0 mol of the metal magnesium.
 27. The nonaqueouselectrolytic solution according to claim 21, wherein the quaternaryammonium salt is at least one type selected from the group consisting oftrifluoromethanesulfonic acid tetrabutylammonium,trifluoromethanesulfonic acid tributylmethylammonium,trifluoromethanesulfonic acid triethylmethylammonium, tetrafluoroboricacid tetrabutylammonium, tetrafluoroboric acid tributylmethylammonium,tetrafluoroboric acid triethylmethylammonium,tetrabutylammoniumbis(trifluoromethanesulfonyl)imide,tributylmethylammoniumbis(trifluoromethanesulfonyl)imide, andtriethylmethylammoniumbis(trifluoromethanesulfonyl)imide, and the1,3-alkylmethylimidazolium salt is at least one kind selected from thegroup consisting of a 1,3-dimethylimidazoliumtetrafluoroborate, a1-ethyl-3-methylimidazoliumtetrafluoroborate, a1-butyl-3-methylimidazoliumtetrafluoroborate,1,3-dimethylimidazoliumbis(trifluoromethanesulfonyl)imide,1-ethyl-3-methylimidazoliumbis(trifluoromethanesulfonyl)imide, and1-butyl-3-methylimidazoliumbis(trifluoromethanesulfonyl)imide.
 28. Thenonaqueous electrolytic solution according to claim 21, wherein any oneof the quaternary ammonium salt or the 1,3-alkylmethylimidazolium saltis added at the ratio of equal to or more than 1.0 mol and equal to orless than 2.0 mol per 1.0 mol of the metal magnesium, or the quaternaryammonium salt and the 1,3-alkylmethylimidazolium salt are added at theratio of equal to or more than 1.0 mol and equal to or less than 2.0 molin total per 1.0 mol of the metal magnesium.
 29. The nonaqueouselectrolytic solution according to claim 21, wherein the ether systemorganic solvent is 1,2-dimethoxyethane.
 30. The nonaqueous electrolyticsolution according to claim 21, wherein the metal magnesium is added atthe ratio of equal to or more than 0.25 mol/l and equal to or less than1.0 mol/l to the ether system organic solvent.
 31. An electrochemicaldevice, comprising: a first electrode; a second electrode; and anonaqueous electrolytic solution, the nonaqueous electrolyte solutionincluding magnesium ions dissolved in an ether system organic solvent inwhich at least one of metal magnesium, alkyl trifluoromethanesulfonatehaving a general formula RCF₃SO₃, a quaternary ammonium salt having ageneral formula R¹R²R³R⁴N⁺N⁻ and a 1,3-alkyl methylimidazolium salthaving a general formula R(C₃H₃N₂)CH₃]⁺X⁻ are added to the ether systemorganic solvent; wherein in the general formula RCF₃SO₃, R is a methylgroup or an ethyl group; wherein in the general formula R¹R²R³R⁴N⁺Z⁻,each of R¹, R², R³, and R⁴ is an alkyl group or an aryl group, and Z⁻ isany one of a chloride ion (Cl⁻), a bromide ion (Br⁻), an iodine ion(I⁻), an acetic acid ion (CH₃COO⁻), a perchloric acid ion (ClO₄ ⁻), atetrafluoroboric acid ion (BF₄ ⁻), a hexafluorophosphoric acid ion (PF₆⁻), a hexafluoroarsenic acid ion (AsF₆ ⁻), a perfluoroalkylsulfonic acidion (Rf1SO₃) where Rf1 is a perfluoroalkyl group, and aperfluoroalkylsulfonyl imide ion ((Rf2SO₂)₂N) where Rf2 is aperfluoroalkyl group; wherein in the general formula [R(C₃H₃N₂)CH₃]⁺X⁻,R is a methyl group, an ethyl group or a butyl group, and X⁻ is any oneof a tetrafluoroboric acid ion (BF₄ ⁻) and abis(trifluoromethanesulfonyl)imide ion ((SO₂CF₃)₂N⁻); and wherein anactive material of the second electrode is oxidized to generatemagnesium ions.
 32. The electrochemical device according to claim 31,wherein the active material of the first electrode is made from any oneof a compound which reacts with the magnesium ion and a compound whichoccludes the magnesium ion, and wherein the active material of thesecond electrode is made from any one of a metal single body ofmagnesium and an alloy containing magnesium.
 33. The electrochemicaldevice according to claim 31, wherein the first electrode is a positiveelectrode including a positive-electrode active material made from agraphite fluoride and a positive-electrode mixture containing copper,and the second electrode is a negative electrode containing any one of amagnesium metal and a magnesium alloy as a negative-electrode activematerial.
 34. The electrochemical device according to claim 31, whereinthe first electrode is a positive electrode including apositive-electrode mixture containing a positive-electrode activematerial made from a graphite fluoride, the second electrode is anegative electrode containing any one of a magnesium metal and amagnesium alloy as the negative-electrode active material, and theelectrochemical device has at least one of a positive-electrode powercollecting body made of at least one of a conductive material coveredwith copper and copper; and a positive-electrode can having an innersurface covered with copper contacting therein the positive-electrodeactive material.
 35. The electrochemical device according to claim 31,wherein the electrochemical device is configured as a battery.
 36. Anelectrochemical device configured as a magnesium battery, comprising: anegative-electrode active material containing any one of a magnesiummetal and a magnesium alloy; and a positive-electrode mixture containinga positive-electrode active material made of a graphite fluoride, andcopper.
 37. The electrochemical device according to claim 36, whereincopper is contained at a mass ratio of equal to or larger than 3 andequal to or smaller than 15 per a mass ratio of 100 of the graphitefluoride in the positive-electrode mixture.
 38. The electrochemicaldevice according to claim 36, wherein the copper is contained at a massratio of at least 15 per a mass ratio of 100 of the graphite fluoride inthe positive-electrode mixture.
 39. The electrochemical device accordingto claim 36, further having a separator; wherein the negative-electrodeactive material is disposed on one side of the separator, and thepositive-electrode mixture is disposed on another side of the separator.40. An electrochemical device configured as a magnesium battery,comprising: a negative-electrode active material containing therein anyone of a magnesium metal and a magnesium alloy; a positive-electrodemixture containing therein a positive-electrode active material madefrom a graphite fluoride; and at least one of a positive-electrode powercollecting body made of at least one of a conductive material coveredwith copper and copper; and a positive-electrode can having an innersurface covered with copper containing the positive-electrode activematerial.